Page summary

https://www.wikidata.org/wiki/Wikidata:Main_Page

Tested 2026-07-28 02:25:58 using Chrome 150.0.7871.186 (runtime settings)

SummaryWaterfallMetricsRenderingCoachPageXrayCPU

This page is fast to paint, snappy to interact with and visually stable, but loose on best practices and weak on user privacy.

80 / 100
Coach overall
84 / 100
Performance
73 / 100
Best practice
76 / 100
Privacy

How it loaded →

0 → 1.666 s · median run
Frame at 0 ms
start
Frame at 900 ms
900 ms
Frame at 1100 ms
1.100 s
Frame at 1200 ms
1.200 s
Frame at 1400 ms
1.400 s
Frame at 1700 ms
Complete1.700 s
866 ms
First Visual Change
1.015 s
Speed Index
1.533 s
Visual Complete 85%
1.666 s
Last Visual Change
TTFB404 msLCP1.520 sTBT29 msCLS0.00

What to act on · top recommendations

Serve images in modern formats (AVIF, WebP)

0 / 100

The page ships 20 images (out of 20) in JPEG/PNG/GIF without a modern alternative. Wrap them in a <picture> with a <source type="image/avif"> or "image/webp" before the legacy <img>, or serve modern formats from your image pipeline directly. AVIF and WebP usually deliver 25–50% smaller files at the same quality.

Avoid extra requests by setting cache headers

0 / 100

The page has 23 requests that are missing a cache time. Configure a cache time so the browser doesn't need to download them every time. It will save 205.5 kB the next access.

Total JavaScript size shouldn't be too big

0 / 100

The total JavaScript transfer size is 655.7 kB and the uncompressed size is 2.8 MB. This is totally crazy! There is really room for improvement here.

Google Web Vitals

min · median · mean · max of 5 runs
MetricMinMedianMeanMaxRuns agree?
Time To First Byte (TTFB)402 ms404 ms405 ms412 msstable ±1%
Largest Contentful Paint (LCP)1.488 s1.520 s1.515 s1.528 sstable ±1%
Cumulative Layout Shift (CLS)0.00490.00490.00490.0049identical

Visual Metrics

min · median · mean · max of 5 runs
MetricMinMedianMeanMaxRuns agree?
First visual change833 ms866 ms859 ms866 msstable ±2%
Last visual change1.633 s1.666 s1.653 s1.666 sstable ±1%
Speed index992 ms1.015 s1.014 s1.025 sstable ±2%
Largest image1.467 s1.533 s1.520 s1.533 sstable ±2%
Largest contentful paint1.467 s1.533 s1.520 s1.533 sstable ±2%
Last meaningful paint1.467 s1.533 s1.520 s1.533 sstable ±2%
Visual readiness767 ms800 ms793 ms800 msstable ±2%
Visual complete 851.467 s1.533 s1.520 s1.533 sstable ±2%
Visual complete 951.633 s1.666 s1.653 s1.666 sstable ±1%
Visual complete 991.633 s1.666 s1.653 s1.666 sstable ±1%

CPU

min · median · mean · max of 5 runs
MetricMinMedianMeanMaxRuns agree?
Total Blocking Time20 ms29 ms28 ms33 msruns disagree ±22%
Max Potential FID70 ms79 ms78 ms83 msvaries ±8%
CPU long tasks 2223runs disagree ±25%
CPU last long task happens at1.464 s1.509 s1.501 s1.515 sstable ±2%

More metrics

min · median · mean · max of 5 runs
MetricMinMedianMeanMaxRuns agree?
First paint864 ms864 ms865 ms868 msstable ±1%
Load event end1.888 s1.962 s1.949 s1.969 sstable ±2%

User Timing

min · median · mean · max of 5 runs
MetricMinMedianMeanMaxRuns agree?
mwStartup807 ms818 ms815 ms820 msstable ±1%

Waterfall

Run 2 SpeedIndex median

First paintFCPLCPDOMContentLoadedDOM interactiveLoadRender-blockingRedirectError

Rendering

Run 2 · median
0.000 s
0s0.5s1s1.5s

The red band on the timeline marks when the main thread was busy with long tasks: moments when the page could not paint or respond, however the video looks.

Download video

Filmstrip

10 frames

Use --filmstrip.showAll to show all filmstrips.

Frame at 0 ms
0 ms
0 %
Frame at 700 ms
700 ms
0 %
Frame at 900 ms
900 ms
75 %
Frame at 1.000 s
1.000 s
76 %
Frame at 1.100 s
1.100 s
78 %
Frame at 1.200 s
1.200 s
81 %
Frame at 1.300 s
1.300 s
82 %
Frame at 1.400 s
1.400 s
83 %
Frame at 1.600 s
1.600 s
90 %
Frame at 1.700 s
1.700 s
100 %

Click a frame to seek the video to that moment. The dot marks frames where the page changed visually.

Visual instability

19.84 % of pixels ever changed · 0 % changed 5+ times
Heatmap of how often each pixel changed while the page loaded

The whole recording in one image: every pixel is tinted by how often it changed. Amber changed once, deep red changed ten or more times. The scale is fixed, so heatmaps from different runs compare directly.

Flat amber is a page that painted once and stayed put. Red speckle in the shape of the text means the same pixels repainted over and over, usually invisible rendering noise that inflates Last Visual Change and Speed Index. A solid red block is a genuinely restless area, like an ad or a carousel.

Frames

How smoothly Chrome delivered frames to the screen during the test. Dropped counts only frames Chrome flags as affecting smoothness. On mostly-static pages the longest gap includes idle time where there was simply nothing to draw.

Frames shown18
Partial1
Dropped2
Effective FPS17.1
Longest gap207 msat 1.649 s

Why was rendering delayed?

Rendering was not meaningfully delayed. First paint landed at 864 ms on a 404 ms first byte; the 2 render-blocking requests were done by 618 ms and the remaining ~246 ms is style and layout work (46 ms of it measured style recalculation). The largest paint followed at 1.520 s.

Style recalculation

measured by Chrome during this run

Style the browser had to recalculate before it could paint: many elements or a lot of time spent here points at expensive CSS on the critical rendering path. The recalculation count and the largest single one tell the two problems apart: one massive style change touching most of the page (few recalculations, the largest close to the total) needs different medicine than thousands of tiny ones (many recalculations, each tiny).

One large recalculation dominates. Restyling 2 181 elements cost 46 ms before the page painted (5.4 % of the time to First Contentful Paint), and a single recalculation of 2 155 elements accounts for 45 ms of it. Look for one class or inline-style change on a large container near the top of the DOM that restyles the whole subtree at once. The changes driving it are listed under Style invalidations below.

Before first contentful paint

Recalculations11
Elements2181
Total time46.441 ms
Largest recalculation2155 elements · 44.994 ms

Before largest contentful paint

Recalculations14
Elements2239
Total time50.694 ms
Largest recalculation2155 elements · 44.994 ms

The recalculation work before first paint is 5.4 % of the time to First Contentful Paint.

Render blocking requests

3 requests · 62.8 KB

Blocking requests delay both paints: the browser renders nothing until they arrive, so they push First Contentful Paint and everything after it, including the largest paint (LCP). Requests that block the parser inside the body stall everything after them in the document. Load JavaScript with defer or async, and keep non-critical CSS off the critical path with media attributes. Bars show when each request loaded on a clock that runs to the last paint (the dashed line is FCP, the clock ends at LCP); the gap after the bars is style and layout work.

RequestWhen it loadedTransferDownload
document
www.wikidata.org · TTFB 404 ms
546 ms
47.3 KB545 ms
site.stylesblocking
css · load.php styles batch · www.wikidata.org
196 ms
2.5 KB196 ms
ext.discussionTools.init.styles + 13 more modulesblocking
css · load.php styles batch · www.wikidata.org
192 ms
37.3 KB192 ms
startuppotentially blocking
javascript · load.php startup · www.wikidata.org
230 ms
23.0 KB230 ms
LCP resource
1920px-Wikidata_nodes_in_white.svg.png — downloaded by 1.413 s, rendered at 1.520 s
858 ms
77.0 KB858 ms
0380 ms1.140 sFCP 864 msLCP 1.520 s

Slowest CSS selectorsProfile run

How long Chrome spent testing each CSS selector against the page while recalculating styles. A selector with many match attempts and zero matches is evaluated against the document over and over for rules that never apply.

Not worth optimizing on this page. All selector matching cost 20 ms, and the worst single selector 0.39 ms. The tables are kept for reference.

Matching time20 ms
Match attempts344 192
Matches15 695
Show the selector tables anyway

Selectors by matching time

top 25
SelectorTimeAttemptsMatches
.vector-pinnable-element .mw-list-item a:not(.mw-selflink):visited0.39 ms1 722448
a:where(:not([role="button"])):visited0.37 ms1 722847
body.mw-mmv-lightbox-open > :not(.mw-notification-area-overlay)0.37 ms1 6450
a:where(:not([role="button"])):visited:hover0.29 ms1 7224
a:where(:not([role="button"])):visited:active0.29 ms1 7220
.ve-not-available a:has(+ .mw-editsection-divider + a.mw-editsection-visualeditor:last-of-type)::after0.25 ms8610
.vector-dropdown-content .mw-list-item a:not(.mw-selflink):visited0.22 ms1 722448
a:visited0.22 ms1 722847
.vector-pinnable-element .mw-list-item0.20 ms1 341736
a:not([href])0.20 ms8610

Wasted selector work: attempts that never match

top 25
SelectorAttemptsTime
.mw-mf.ns-talk.ext-discussiontools-replytool-enabled.ext-discussiontools-init-lede-hidden .mw-body-content > .mw-parser-output > .mf-section-0 > :not(.ext-discussiontools-emptystate)3 8170.10 ms
.center *3 8170.13 ms
.oo-ui-actionFieldLayout .oo-ui-actionFieldLayout-input > .oo-ui-textInputWidget > .oo-ui-inputWidget-input:hover ~ *3 8170.18 ms
.oo-ui-checkboxInputWidget *3 8170.14 ms
figure[typeof~="mw:File/Thumb"] > :not(figcaption)3 8170.14 ms
.mw-mf.ns-talk.ext-discussiontools-replytool-enabled.ext-discussiontools-init-lede-hidden .mw-body-content > .mw-talkpageheader > :not(.ext-discussiontools-emptystate)3 8170.18 ms
.oo-ui-actionFieldLayout .oo-ui-actionFieldLayout-input > .oo-ui-textInputWidget > .oo-ui-inputWidget-input:focus ~ *3 8170.10 ms
.cdx-message__content > :last-child3 8170.13 ms
.oo-ui-actionFieldLayout .oo-ui-actionFieldLayout-input > .oo-ui-textInputWidget.oo-ui-flaggedElement-invalid > .oo-ui-inputWidget-input ~ *3 8170.16 ms
figure[typeof~="mw:File/Frame"] > :not(figcaption)3 8170.11 ms

Style invalidationsProfile run

Why the browser had to recalculate style and layout: every DOM/style change invalidates some set of nodes, and the same class or attribute churning over and over is the pattern to hunt. Counts, not milliseconds: the time is in the style recalculation numbers above.

Chase what keeps changing after the page is up. 1 701 style recalculations and 1 509 layout invalidations fired after first paint, on a page the user was already looking at. The biggest driver is attribute style (371×). Start with the script under "Scripts causing invalidations" that keeps triggering it.

Style recalculations1 7201 701 after first paint
Layout invalidations4 0251 509 after first paint

Changes that keep invalidating

top 13
  • attribute: style371×
  • attribute: title18×
  • attribute: class11×
  • attribute: href
  • pseudo: visited
  • attribute: width
  • pseudo: disabled
  • pseudo: enabled
  • attribute: disabled
  • class: vector-animations-ready
  • class: ve-not-available
  • class: ext-discussiontools-init-ready
  • class: ve-init-mw-desktopArticleTarget-targetContainer

Invalidation reasons

split at first paint

Between first and largest paint

Invalidations while the largest paint was still pending, so these delayed it.

ReasonStyle recalculationsLayout
A node was inserted into the page2
An element entered layout4
An element's size changed3
Unknown1
An SVG element changed1

After the largest paint

Churn on the fully rendered page: wasted work and possible jank, but no paint delay.

ReasonStyle recalculationsLayout
Related style rule1 218
JavaScript changed an inline styleSet a class instead of writing element.style, so the browser can batch the work.370
A stylesheet rule changed87
A node was inserted into the page18
Attribute6
An element entered layout121
An element left layout1 369
A style change forced layout10

Before first paint: building the page

The page being constructed and styled for the first render. Expected work, shown for scale.

ReasonStyle recalculationsLayout
A stylesheet rule changed1
A node was inserted into the page17
A pseudo-class state changed (:hover, :focus, …)1
An element entered layout2 493
An element left layout2
An element's size changed9
A style change forced layout1
Unknown7
An SVG element changed2
Scrollbar changed2

Scripts causing invalidations

top 9

Coach

The coach helps you find performance problems on your web page using web performance best practice rules. And gives you advice on privacy and best practices. Tested using Coach-core version 9.2.1.

Performance advice

84
11 warnings3 info
warn(0)Serve images in modern formats (AVIF, WebP)modernImageFormats

The page ships 20 images (out of 20) in JPEG/PNG/GIF without a modern alternative. Wrap them in a <picture> with a <source type="image/avif"> or "image/webp" before the legacy <img>, or serve modern formats from your image pipeline directly. AVIF and WebP usually deliver 25–50% smaller files at the same quality.

AVIF and WebP routinely deliver 25–50% smaller files than JPEG and PNG at the same perceived quality, and every browser version still under support understands at least one of them. Ship modern formats either through a <picture> element with <source type="image/avif"> / "image/webp" entries in front of the legacy <img>, or directly from a content-negotiating image pipeline that returns AVIF / WebP when the client accepts it. https://web.dev/articles/serve-images-webp

Offenders
warn(0)Avoid extra requests by setting cache headerscacheHeaders

The page has 23 requests that are missing a cache time. Configure a cache time so the browser doesn't need to download them every time. It will save 205.5 kB the next access.

The easiest way to make your page fast is to avoid doing requests to the server. Setting a cache header on your server response will tell the browser that it doesn't need to download the asset again during the configured cache time! Always try to set a cache time if the content doesn't change for every request.

Offenders
warn(0)Total JavaScript size shouldn't be too bigjavascriptSize

The total JavaScript transfer size is 655.7 kB and the uncompressed size is 2.8 MB. This is totally crazy! There is really room for improvement here.

A lot of JavaScript often means you are downloading more than you need. How complex is the page and what can the user do on the page? Do you use multiple JavaScript frameworks?

Offenders
URLTransferContent
https://www.wikidata.org/w/load.php?lang=en&modules=startup&only=scripts&raw=1&skin=vector-202223.0 KB69.2 KB
https://www.wikidata.org/w/load.php...ta.org/w/load.php2.8 KB5.1 KB
https://www.wikidata.org/w/load.php...ta.org/w/load.php17.8 KB60.5 KB
https://www.wikidata.org/w/load.php...ta.org/w/load.php348.7 KB1.5 MB
https://www.wikidata.org/w/load.php...ta.org/w/load.php2.8 KB14.9 KB
https://www.wikidata.org/w/load.php...ta.org/w/load.php126.9 KB516.2 KB
https://www.wikidata.org/w/load.php...ta.org/w/load.php14.9 KB39.8 KB
https://www.wikidata.org/w/load.php...ta.org/w/load.php88.7 KB388.7 KB
https://auth.wikimedia.org/metawiki/wiki/Special:CentralAutoLogin/checkLoggedIn...gin/checkLoggedIn1.5 KB254 B
https://www.wikidata.org/w/load.php...ta.org/w/load.php11.6 KB75.4 KB
https://www.wikidata.org/w/load.php...ta.org/w/load.php1.8 KB1.8 KB
warn(13)Lazy-load below-the-fold imageslazyLoadingImages

The page has 14 below-the-fold images without loading="lazy". Add loading="lazy" so the browser defers downloading and decoding them until the user scrolls them into view.

Adding loading="lazy" to an <img> tells the browser not to download or decode it until it is close to the viewport. For images that the user may never see (deep in the page, behind a tab, in a footer carousel), this saves bandwidth and main-thread time during initial render. The LCP image and any image in the initial viewport should NOT be lazy-loaded — that delays the first paint. https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img#loading

Offenders
warn(60)Avoid CPU Long TaskslongTasks

The page has 2 CPU long tasks with the total of 246 ms. The total blocking time is 33 ms and 1 long task before first contentful paint with total time of 163 ms. However the CPU Long Task is depending on the computer/phones actual CPU speed, so you should measure this on the same type of the device that your user is using. Use Geckoprofiler for Firefox or Chromes tracelog to debug your long tasks.

Long CPU tasks locks the thread. To the user this is commonly visible as a "locked up" page where the browser is unable to respond to user input; this is a major source of bad user experience on the web today. However the CPU Long Task is depending on the computer/phones actual CPU speed, so you should measure this on the same type of the device that your user is using. To debug you should use the Chrome timeline log and drag/drop it into devtools or use Firefox Geckoprofiler.

Offenders
  • unknown
  • self
warn(70)Apply the right priority hints to the LCP imagelcpImageHints

The LCP image is missing fetchpriority="high". Adding it tells the browser to fetch the image with high priority instead of the default heuristic (which often deprioritises hero images that are loaded after the HTML has been parsed).

When the Largest Contentful Paint element is an image, the browser priority hints applied to that element directly affect the LCP metric. The image must NOT be loading="lazy" (that defers the fetch until near-viewport, which is the opposite of what an LCP image needs) and SHOULD be fetchpriority="high" (so the browser fetches it with high priority instead of guessing). https://web.dev/articles/fetch-priority

Offenders
  • <img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a3/Wikidata_nodes_in_white.svg/1920px-Wikidata_nodes_in_white.svg.png?utm_source=www.wikidata.org&amp;utm_campaign=parser&amp;utm_content=thumbnail" decoding="async" width="1285" height="340" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a3/Wikidata_nodes_in_white.svg/3840px-Wikidata_nodes_in_white.svg.png?utm_source=www.wikidata.org&amp;utm_campaign=parser&amp;utm_content=thumbnail 2x" data-file-width="1285" data-file-height="340">
warn(80)Don't scale images in the browseravoidScalingImages

The page has 2 images that are scaled more than 100 pixels. It would be better if those images are sent so the browser don't need to scale them.

It's easy to scale images in the browser and make sure they look good in different devices, however that is bad for performance! Scaling images in the browser takes extra CPU time and will hurt performance on mobile. And the user will download extra kilobytes (sometimes megabytes) of data that could be avoided. Don't do that, make sure you create multiple version of the same image server-side and serve the appropriate one.

Offenders
warn(80)Don't use private headers on static contentprivateAssets

The page has 3 requests with private headers. The main page has a private header. It could be right in some cases where the user can be logged in and served specific content. But if your asset is static it should never be private. Make sure that the assets really should be private and only used by one user. Otherwise, make it cacheable for everyone.

If you set private headers on content, that means that the content are specific for that user. Static content should be able to be cached and used by everyone. Avoid setting the cache header to private.

Offenders
infoAdd decoding="async" to non-critical imagesdecodingAsync

The page has 4 images (out of 24) without a decoding hint. Add decoding="async" to non-critical images so the browser can decode them off the main thread.

Setting decoding="async" on an <img> tells the browser it can decode the image off the main thread, which keeps the page responsive to user interactions while images are being processed. The default ("auto") leaves the choice to the browser. https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img#decoding

Offenders
infoLong cache headers is goodcacheHeadersLong
warn(90)Avoid doing redirectsassetsRedirects

The page has 1 redirect. 1 of the redirects are from the base domain, please fix them!

A redirect is one extra step for the user to download the asset. Avoid that if you want to be fast. Redirects are even more of a showstopper on mobile.

Offenders
infoMake each CSS response smalloptimalCssSize

https://www.wikidata.org/w/load.php?lang=en&modules=ext.discussionTools.init.styles%7Cext.uls.pt%7Cext.visualEditor.desktopArticleTarget.noscript%7Cext.wikimediamessages.styles%7Cmediawiki.page.gallery.styles%7Cmediawiki.widgets.styles%7Coojs-ui-core.icons%2Cstyles%7Coojs-ui.styles.indicators%7Cskins.vector.icons%2Cstyles%7Cskins.vector.search.codex.styles%7Cwikibase.client.init%7Cwikibase.vector.scopedTypeaheadSearchStyles&only=styles&skin=vector-2022 size is 38.2 kB (38175) and that is bigger than the limit of 25 kB. Try to keep each CSS response under 25 kB.

Render-blocking CSS holds up the first paint until it has fully downloaded, parsed and applied, so smaller CSS files mean a faster start. Split your CSS into a small critical bundle inlined or eagerly loaded, with the rest lazy-loaded.

Offenders
URLTransferContent
https://www.wikidata.org/w/load.php...ta.org/w/load.php37.3 KB318.3 KB
warn(95)Inline CSS for faster first renderinlineCss

The page has both inline CSS and CSS requests even though it uses a HTTP/2-ish connection. If you have many users on slow connections, it can be better to only inline the CSS. Run your own tests and check the waterfall graph to see what happens.

In the early days of the Internet, inlining CSS was one of the ugliest things you can do. That has changed if you want your page to start rendering fast for your user. Always inline the critical CSS when you use HTTP/1 and HTTP/2 (avoid doing CSS requests that block rendering) and lazy load and cache the rest of the CSS. It is a little more complicated when using HTTP/2. Does your server support HTTP push? Then maybe that can help. Do you have a lot of users on a slow connection and are serving large chunks of HTML? Then it could be better to use the inline technique, becasue some servers always prioritize HTML content over CSS so the user needs to download the HTML first, before the CSS is downloaded.

warn(99)Avoid slowing down the critical rendering pathavoidRenderBlocking

The page has 2 blocking requests and 0 in body parser blocking (0 JavaScript and 2 CSS). There are 1 potentially render blocking requests. You need to verify if it is render blocking: https://www.wikidata.org/w/load.php?lang=en&modules=startup&only=scripts&raw=1&skin=vector-2022

The critical rendering path is what the browser needs to do to start rendering the page. Every file requested inside of the head element will postpone the rendering of the page, because the browser need to do the request. Avoid loading JavaScript synchronously inside of the head (you should not need JavaScript to render the page), request files from the same domain as the main document (to avoid DNS lookups) and inline CSS for really fast rendering and a short rendering path.

Offenders

Best practice advice

73
2 warnings4 info
infoMeta descriptionmetaDescription

The page is missing a meta description.

Use a page description to make the page more relevant to search engines.

infoAvoid unnecessary headersunnecessaryHeaders

There are 18 responses that sets both a max-age and expires header. There are 44 responses that sets a server header.

Do not send headers that you don't need. We look for p3p, cache-control and max-age, pragma, server and x-frame-options headers. Have a look at Andrew Betts - Headers for Hackers talk as a guide https://www.youtube.com/watch?v=k92ZbrY815c or read https://www.fastly.com/blog/headers-we-dont-want.

Offenders
warn(50)Set a sensible viewport meta tagviewport

The viewport meta tag does not contain width=device-width, the browser may use a desktop-width fallback.

The viewport meta tag tells the browser how to lay out the page on small screens. Without it (or without width=device-width) the page is rendered at a desktop fallback width and scaled down, which makes text unreadable on mobile. Disabling zoom (user-scalable=no, maximum-scale<=1) is also an accessibility regression. https://developer.mozilla.org/en-US/docs/Web/HTML/Viewport_meta_tag

warn(50)Avoid too many third party requeststhirdParty

The page do 50% requests to third party domains (22 requests and 205.5 kB). First party is 22 requests and 753.7 kB. The regex .*wikidata.* was used to calculate first/third party requests.

Do not load most of your content from third party URLs.

infoGive every image a textual alternativeimageAltText

The page has 4 images without an alt attribute. Add alt="..." with a description, or alt="" if the image is purely decorative.

Every <img> needs an alt attribute. Use alt="meaningful description" for content images so assistive technologies can announce them, or alt="" (or role="presentation" / aria-hidden="true") for purely decorative images so they are skipped. A missing alt attribute leaves screen reader users with no information at all. https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img#alt

Offenders
infoDo not send too long headerslongHeaders

https://www.wikidata...ikidata:Main_Page has a header content-security-policy that is 4501 characters long. https://www.wikidata...ta.org/w/load.php has a header sourcemap that is 1099 characters long.

Do not send response headers that are too long.

Offenders

Privacy advice

76
5 warnings2 info
infoSet a Cross-Origin-Embedder-Policy header so cross-origin subresources opt in to being embedded.crossOriginEmbedderPolicyHeader

Set a Cross-Origin-Embedder-Policy header (typically require-corp or credentialless) on the document response to control cross-origin embedding.

Cross-Origin-Embedder-Policy (COEP) makes the page refuse to load cross-origin subresources unless they explicitly opt in via CORP or CORS. Together with Cross-Origin-Opener-Policy it puts the page in a cross-origin isolated context, which mitigates cross-window side-channel attacks (Spectre) and unlocks high-resolution timers and SharedArrayBuffer. https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cross-Origin-Embedder-Policy

Offenders
warn(0)Set a Cross-Origin-Opener-Policy header to isolate the page from cross-origin windows.crossOriginOpenerPolicyHeader

Set a Cross-Origin-Opener-Policy header (typically same-origin) on the document response to isolate the page from cross-origin windows.

Cross-Origin-Opener-Policy (COOP) lets a page sever its window-group ties to cross-origin documents that opened it or that it opens. Together with Cross-Origin-Embedder-Policy it puts the page in a cross-origin isolated context, which mitigates cross-window side-channel attacks (Spectre) and unlocks high-resolution timers and SharedArrayBuffer. https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cross-Origin-Opener-Policy

Offenders
infoSet a Cross-Origin-Resource-Policy header to limit who may embed the page.crossOriginResourcePolicyHeader

Set a Cross-Origin-Resource-Policy header (same-origin, same-site or cross-origin) on the document response to limit who may embed it.

Cross-Origin-Resource-Policy (CORP) is a per-response opt-in that tells the browser which origins are allowed to embed the resource. It blocks cross-origin or cross-site no-cors embedding (img, script, iframe, etc.) and is one of the building blocks of cross-origin isolation. https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cross-Origin-Resource-Policy

Offenders
warn(0)Set a Permissions-Policy header to control which browser features the page can use.permissionsPolicyHeader

Set a Permissions-Policy header to control which browser features the page can use.

The Permissions-Policy response header (the successor to Feature-Policy) lets a site explicitly opt in or out of powerful browser features such as camera, microphone, geolocation, payment and clipboard. Setting a strict policy reduces the attack surface and limits what embedded third parties can do. https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Permissions-Policy

Offenders
warn(0)Set a referrer-policy header to make sure you do not leak user information.referrerPolicyHeader

Set a referrer-policy header to make sure you do not leak user information.

Referrer Policy is a new header that allows a site to control how much information the browser includes with navigations away from a document and should be set by all sites. https://scotthelme.co.uk/a-new-security-header-referrer-policy/.

Offenders
warn(0)Avoid third party cookies that is used to track the user.thirdPartyCookies

The page sets 21 third party cookies.

Third party cookies are used to track the user. They are automatically blocked in Safari and Firefox.

Offenders
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
  • upload.wikimedia.org
warn(30)Use a strict Content-Security-Policy header to mitigate cross-site scripting (XSS) attacks.contentSecurityPolicyHeader

The policy allows 'unsafe-inline', which lets the browser execute inline scripts and styles directly from the page. Move to nonces or hashes plus 'strict-dynamic' so that inline injection cannot run. The policy allows 'unsafe-eval', which lets the page call eval() and Function(). Almost no application needs this; remove it.

A Content-Security-Policy response header tells the browser which sources of script, style, and other content are allowed. The most effective form is a strict CSP using nonces or hashes together with strict-dynamic; the worst is a missing header, with unsafe-inline and unsafe-eval close behind. https://web.dev/articles/strict-csp

Page info

A snapshot of what the browser actually built for this page: the document, how big and deep the DOM tree is and what it kept in storage. Big, deep trees are slower to style and lay out, so the counts Chrome warns about carry a flag.

Page info

Document

What the page says it is and how large it rendered.

TitleWikidataThe document title, shown in the browser tab and used by search results.
GeneratorMediaWiki 1.47.0-wmf.12The tool or CMS that generated the HTML, from the page generator meta tag.
Layout viewport1904 × 2751 pxThe width the page laid out at, and the full height of the rendered document.

DOM structure

How much markup the browser has to build, style and lay out.

DOM elements1,923Very large, slows layout and styleTotal HTML elements. Fewer means less for the browser to style, lay out and paint.
Avg DOM depth14How deeply elements are nested on average.
Max DOM depth23The deepest nesting on the page. Deep branches cost more style recalculation.
Iframes0No embedded documents on this page.
Script tags4Number of script elements. More scripts usually means more main-thread work.

Storage and connection

What the page stored on the client, and the network it was tested on.

Local storage1.2 MBData the page saved in localStorage, kept across visits.
Session storage0 bData kept in sessionStorage for this tab session only.
Connection type3GWhat the Network Information API reported for the test connection.

Resource hints

3 hints
dns-prefetch
  • https://meta.wikimedia.org/
  • https://www.wikidata.org/wiki/auth.wikimedia.org
preconnect
  • https://upload.wikimedia.org/

Technologies used to build the page

Data collected using Coach-core version 9.2.1. With updated code from Webappanalyzer 2026-05-04. Use --browsertime.firefox.includeResponseBodies html or --browsertime.chrome.includeResponseBodies html to help Wappalyzer find more information about technologies used.

Detected technologies

4 technologies

Data from run 2

Visual Metrics

Visual milestones

all times from navigation start
Speed Index1.01 show quickly the page looked done
First Visual Change0.87 sfirst paint reaches the screen
Last Visual Change1.67 sscreen stops changing · 0.80 s after first
nothing painted yet
First Visual Change0.87 s
Visual Complete 85%1.53 s
Visual Complete 95% · Visual Complete 99% · Last Visual Change1.67 s
Visual Readiness0.80 s· first to last change
00.5 s1.0 s1.5 s
Visual progress
Visual progress at 0 s0.0s
Visual progress at 0.7 s0.7s
Visual progress at 1 s1.0s
Visual progress at 1.1 s1.1s
Visual progress at 1.2 s1.2s
Visual progress at 1.3 s1.3s
Visual progress at 1.6 s1.6s
Visual progress at 1.7 s1.7s
FCP0.86s
LCP1.52s
VC851.53s
Long tasks
0.0s0.3s0.7s1.0s1.4s1.7s

Google Web Vitals

from run 2

Largest Contentful Paint

When the page main content is rendered, collected via the Largest Contentful Paint API. Read more about Largest Contentful Paint.

1.520 sLCP render time

Phase breakdown

  • TTFB404 ms
  • Resource load delay154 ms
  • Resource load duration859 ms
  • Element render delay103 ms

Element

Element type
<img>
Size (w × h)
414800
URL
https://upload.wikim..._in_white.svg.png
Load time
1.452 s
Style recalculation before LCP
14 recalculations touching 2239 elements (50.694 ms) — the largest touched 2155 elements (44.994 ms)

DOM path

body > div:eq(2) > div > div:eq(2) > main#content > div#bodyContent > div#mw-content-text > div:eq(0) > div > div:eq(0) > span > a > img
LCP

The LCP element is highlighted in the screenshot. If nothing is highlighted the element was removed before the screenshot or the LCP API couldn't find it.

The Largest Contentful Paint API matched this image:

LCP element

Cumulative Layout Shift

How much the page's content shifts as it loads, collected via the Cumulative Layout Shift API.

0.005cumulative layout shift score

One shift is 100% of your 0.005 CLS. li:eq(2) moved at 1.615 s. Reserve space for whatever renders into that spot, a fixed height or an aspect-ratio box, so later content stops pushing the page around.

Elements that shifted

Worst first, showing shifts of 0.01 and up. Each percentage is that shift's exact share of the score.

The shift is spread across many movements below 0.01, none large enough to single out. Check the video or filmstrip to see what moved.

Layout shift

Elements that shifted by more than 0.01 are highlighted in the screenshot. If an element shifted outside the viewport, it won't appear here. Check the video or filmstrip to see the shift.

Browser Metrics

Navigation Timing
Extra timings
User Timing marks
mwStartup818 ms

Server timings

Timing data the server chose to expose through Server-Timing response headers on the main document — typically backend time, cache status or experiment flags.

Server timings

3 entries
NameDurationDescription
cache0 mshit-front
host0 mscp3070
co_id0 ms153236182

Custom metrics collected through JavaScript

There are no custom configured scripts.

Extra metrics collected using scripting

There are no custom extra metrics from scripting.

Visual Elements2
LargestImage1920px-Wikidata_nodes_in_white.svg.png?utm_source=www.wikidata.org&utm_campaign=parser&utm_content=thumbnail
Display time1.533 s
Position (x, y)206, 139
Size (w × h)1220 × 340
HTML snippet
<img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a3/Wikidata_nodes_in_white.svg/1920px-Wikidata_nodes_in_white.svg.png?utm_source=www.wikidata.org&amp;utm_campaign=parser&amp;utm_content=thumbnail" decoding="async" width="1285" height="340" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a3/Wikidata_nodes_in_white.svg/3840px-Wikidata_nodes_in_white.svg.png?utm_source=www.wikidata.org&amp;utm_campaign=parser&amp;utm_content=thumbnail 2x" data-file-width="1285" data-file-height="340">
LargestImage preview
LargestContentfulPaint1920px-Wikidata_nodes_in_white.svg.png?utm_source=www.wikidata.org&utm_campaign=parser&utm_content=thumbnail
Display time1.533 s
Position (x, y)206, 139
Size (w × h)1220 × 340
HTML snippet
<img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a3/Wikidata_nodes_in_white.svg/1920px-Wikidata_nodes_in_white.svg.png?utm_source=www.wikidata.org&amp;utm_campaign=parser&amp;utm_content=thumbnail" decoding="async" width="1285" height="340" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a3/Wikidata_nodes_in_white.svg/3840px-Wikidata_nodes_in_white.svg.png?utm_source=www.wikidata.org&amp;utm_campaign=parser&amp;utm_content=thumbnail 2x" data-file-width="1285" data-file-height="340">
LargestContentfulPaint preview

PageXray

How the page is built.

HTTP versionHTTP/2.0
Total requests44
Total domains3
Transfer size936.7 KB
Content size3.3 MB
Missing compression0
Cookies2721 third-party

Main document

status 200 · 0 redirects

https://www.wikidata.org/wiki/Wikidata:Main_Page

HeaderValue
accept-ch
accept-rangesbytes
age2035
cache-controlprivate, s-maxage=0, max-age=0, must-revalidate, no-transform
content-encodinggzip
content-languageen
content-length42295
content-security-policyscript-src 'unsafe-eval' blob: 'self' meta.wikimedia.org *.wikimedia.org *.wikipedia.org *.wikinews.org *.wiktionary.org *.wikibooks.org *.wikiversity.org *.wikisource.org wikisource.org *.wikiquote.org *.wikidata.org *.wikifunctions.org *.wikivoyage.org *.mediawiki.org mediawiki.org wikimedia.org *.wmflabs.org *.wmcloud.org *.toolforge.org wss://*.toolforge.org *.jsdelivr.net unpkg.com cdnjs.cloudflare.com raw.githubusercontent.com *.github.com code.jquery.com cdn.mathjax.org use.typekit.net fonts.cdnfonts.com use.fontawesome.com i.ytimg.com rsms.me doi.org localhost https://localhost:* http://localhost:* wss://localhost:* ws://localhost:* *.google.com *.gstatic.com *.googleapis.com *.translate.yandex.net yastatic.net ya.ru radically.github.io cdn.sammdot.ca cdn.fontshare.com viaf.org publicai-proxy.alaexis.workers.dev iiif.archive.org api.flickr.com live.staticflickr.com api.anthropic.com api.openai.com api.publicai.co catalogo.pusc.it parsifal.urbe.it opac.sbn.it overpass-api.de api.openrouteservice.org archive.org *.openstreetmap.org *.waymarkedtrails.org *.thunderforest.com registry.ipe.wiki analytics.ipe.wiki qlever.dev app.goacoustic.com wikipedia-archive.ourworldindata.org api.inaturalist.org inaturalist-open-data.s3.amazonaws.com validator.w3.org db.onlinewebfonts.com fontlibrary.org 'unsafe-inline' auth.wikimedia.org; default-src 'self' data: blob: upload.wikimedia.org https://commons.wikimedia.org meta.wikimedia.org *.wikimedia.org *.wikipedia.org *.wikinews.org *.wiktionary.org *.wikibooks.org *.wikiversity.org *.wikisource.org wikisource.org *.wikiquote.org *.wikidata.org *.wikifunctions.org *.wikivoyage.org *.mediawiki.org mediawiki.org wikimedia.org *.wmflabs.org *.wmcloud.org *.toolforge.org wss://*.toolforge.org *.jsdelivr.net unpkg.com cdnjs.cloudflare.com raw.githubusercontent.com *.github.com code.jquery.com cdn.mathjax.org use.typekit.net fonts.cdnfonts.com use.fontawesome.com i.ytimg.com rsms.me doi.org localhost https://localhost:* http://localhost:* wss://localhost:* ws://localhost:* *.google.com *.gstatic.com *.googleapis.com *.translate.yandex.net yastatic.net ya.ru radically.github.io cdn.sammdot.ca cdn.fontshare.com viaf.org publicai-proxy.alaexis.workers.dev iiif.archive.org api.flickr.com live.staticflickr.com api.anthropic.com api.openai.com api.publicai.co catalogo.pusc.it parsifal.urbe.it opac.sbn.it overpass-api.de api.openrouteservice.org archive.org *.openstreetmap.org *.waymarkedtrails.org *.thunderforest.com registry.ipe.wiki analytics.ipe.wiki qlever.dev app.goacoustic.com wikipedia-archive.ourworldindata.org api.inaturalist.org inaturalist-open-data.s3.amazonaws.com validator.w3.org db.onlinewebfonts.com fontlibrary.org en.wikipedia.org en.wikibooks.org en.wikinews.org en.wikiquote.org en.wikisource.org en.wikiversity.org en.wikivoyage.org en.wiktionary.org www.mediawiki.org commons.wikimedia.org foundation.wikimedia.org incubator.wikimedia.org species.wikimedia.org wikimania.wikimedia.org www.wikifunctions.org auth.wikimedia.org; style-src 'self' data: blob: upload.wikimedia.org https://commons.wikimedia.org meta.wikimedia.org *.wikimedia.org *.wikipedia.org *.wikinews.org *.wiktionary.org *.wikibooks.org *.wikiversity.org *.wikisource.org wikisource.org *.wikiquote.org *.wikidata.org *.wikifunctions.org *.wikivoyage.org *.mediawiki.org mediawiki.org wikimedia.org *.wmflabs.org *.wmcloud.org *.toolforge.org wss://*.toolforge.org *.jsdelivr.net unpkg.com cdnjs.cloudflare.com raw.githubusercontent.com *.github.com code.jquery.com cdn.mathjax.org use.typekit.net fonts.cdnfonts.com use.fontawesome.com i.ytimg.com rsms.me doi.org localhost https://localhost:* http://localhost:* wss://localhost:* ws://localhost:* *.google.com *.gstatic.com *.googleapis.com *.translate.yandex.net yastatic.net ya.ru radically.github.io cdn.sammdot.ca cdn.fontshare.com viaf.org publicai-proxy.alaexis.workers.dev iiif.archive.org api.flickr.com live.staticflickr.com api.anthropic.com api.openai.com api.publicai.co catalogo.pusc.it parsifal.urbe.it opac.sbn.it overpass-api.de api.openrouteservice.org archive.org *.openstreetmap.org *.waymarkedtrails.org *.thunderforest.com registry.ipe.wiki analytics.ipe.wiki qlever.dev app.goacoustic.com wikipedia-archive.ourworldindata.org api.inaturalist.org inaturalist-open-data.s3.amazonaws.com validator.w3.org db.onlinewebfonts.com fontlibrary.org 'unsafe-inline'; object-src 'none'; report-uri /w/api.php?action=cspreport&format=json; report-to csp-report-to-endpoint
content-typetext/html; charset=UTF-8
dateTue, 28 Jul 2026 01:52:26 GMT
last-modifiedTue, 28 Jul 2026 01:50:17 GMT
nel{ "report_to": "wm_nel", "max_age": 604800, "failure_fraction": 0.05, "success_fraction": 0.0}
report-to{ "group": "wm_nel", "max_age": 604800, "endpoints": [{ "url": "https://intake-logging.wikimedia.org/v1/events?stream=w3c.reportingapi.network_error&schema_uri=/w3c/reportingapi/network_error/1.0.0" }] }
reporting-endpointscsp-report-to-endpoint='/w/api.php?action=cspreport&format=json';
servermw-web.eqiad.main-5fc9744499-9fx5n
server-timingcache;desc="hit-front", host;desc="cp3070",co_id;desc="153236182"
strict-transport-securitymax-age=106384710; includeSubDomains; preload
varyAccept-Encoding,X-Subdomain,Cookie,Authorization,User-Agent
x-analytics
x-cachecp3070 miss, cp3070 hit/41
x-cache-statushit-front
x-client-ip138.201.135.103
x-content-type-optionsnosniff
x-request-id5453f2e6-f1d5-4a0e-9dcc-5a1f48baaf21

Response codes

200
4397.7%
302
12.3%

Requests and sizes per content type

6 types

Transfer size936.7 KB

  • javascript68.4%
  • image21.1%
  • html5.0%
  • css4.3%
  • svg1.1%
  • favicon0.18%

Content size3.3 MB

  • javascript79.5%
  • css9.5%
  • html6.0%
  • image4.7%
  • svg0.11%
  • favicon0.03%

Requests43

  • image46.5%
  • javascript25.6%
  • svg18.6%
  • css4.7%
  • html2.3%
  • favicon2.3%
ContentHeader SizeTransfer SizeContent SizeRequests
html0 b47.3 KB205.0 KB1
css0 b39.8 KB322.9 KB2
javascript0 b640.3 KB2.6 MB11
image0 b197.2 KB160.9 KB20
favicon0 b1.6 KB907 B1
svg0 b10.4 KB3.7 KB8
Total0 b936.7 KB3.3 MB43

Data per domain

3 domains
DomainTotal download timeTransfer SizeContent SizeRequests
www.wikidata.org4.202 s736.0 KB3.2 MB22
upload.wikimedia.org15.460 s199.2 KB161.1 KB21
auth.wikimedia.org275 ms1.5 KB254 B1

Expires & last-modified statistics

typeminmedianmax
Expires0 seconds0 seconds1 year
Last modified2 minutes4 weeks13 years

Requests loaded after onLoad event

1 request

Includes requests done after load event end.

ContentTransfer SizeRequests
html0 b0
css0 b0
javascript0 b0
image0 b0
font0 b0
favicon1.6 KB1
Total1.6 KB1

Requests loaded after onContentLoad

10 requests

Includes requests done after DOM content loaded.

ContentTransfer SizeRequests
html0 b0
css0 b0
javascript248.1 KB7
image0 b0
font0 b0
favicon1.6 KB1
svg1.2 KB1
Total251.0 KB10

CoverageProfile run

JavaScript and CSS coverage from the extra profile run made by --enableProfileRun, not from the timed iterations. For JS, Chrome tracks which blocks of each script actually ran: a byte is unused when the innermost block of code around it never ran. For CSS, Chrome records every selector that no element on the page matched during the iteration. Enable with --chrome.coverage on every run, or --enableProfileRun to keep the main run's timing metrics untouched. Unused bytes still cost network, parse and compile time for no benefit. Expand the section below for the full picture.

How is "unused" calculated?

sitespeed.io drives Chrome's V8 profiler and CSS rule tracker via the DevTools Protocol, the same machinery the DevTools Coverage panel uses. The two columns are populated by two different mechanisms.

JavaScript

Browsertime calls Profiler.startPreciseCoverage with detailed (block-level) mode at the start of the iteration and Profiler.takePreciseCoverage at the end. V8 returns nested ranges per function: an outer range covering the function body and inner ranges for sub-blocks (if/else, switch arms, ternaries). Each range has an execution count. A byte is "used" if the innermost range that covers it has count > 0, "unused" if it has count = 0, so we catch both functions that never ran AND dead branches inside functions that did.

CSS

Browsertime calls CSS.startRuleUsageTracking at the start of the iteration and CSS.stopRuleUsageTracking at the end. Chrome returns a flat list of rule-text ranges with a used flag: a rule is "used" if at least one element on the page matched it during the iteration. Both inline <style> blocks and external stylesheets are included.

What "this iteration" means

Coverage reflects only what executed during this run. Code behind a button click stays unused unless the iteration clicked the button. The collection window opens before navigation and closes when measure.stop() is reached, so the only way to count interactions is to drive them between measure.start() and measure.stop() inside a navigation script (pass a .js file as the input instead of a plain URL). Clicks, form fills and waits placed there all count toward "used". --preScript runs before the URL is loaded so it can't interact with the page being measured, and --postScript runs after coverage has already been collected, so neither helps here. Detailed coverage also tells V8 to skip some optimisations, which drifts timing metrics like LCP and TBT; that's why --enableProfileRun is the safer option for production measurement (it collects coverage in a separate iteration that doesn't count towards the medians).

JS total2.6 MB
JS unused1.4 MB
JS unused %53.8%
CSS total718.1 KB
CSS unused664.3 KB
CSS unused %92.5%

Where the bytes go

18 files · tile size is total bytes, tint is unused share

3.3 MB of script and style shipped, and 2.1 MB of it never ran on this page. The biggest win is load.php[scripts:ext.centralNotice.choiceData]: 1.5 MB delivered, 776.7 KB unused, and inside it oojs-ui-core alone ships 151.0 KB of dead code.

load.php[scripts:ext.centralNotice.choiceData]1.5 MB · 51% unused
load.php[scripts:@wikimedia/codex]515.5 KB · 58% unused
inline392.7 KB · 96% unused
load.php[scripts:jquery.chosen]388.6 KB · 73% unused
load.php[styles:ext.discussionTools.init.styles]318.3 KB · 89% unused
load.php[scripts:mediawiki.action.view.postEdit]75.4 KB · 13% unused
load.php[startup]69.2 KB · 9% unused
load.php[scripts:ext.visualEditor.core.utils.parsing]60.5 KB · 76% unused
load.php[scripts:ext.gadget.formWizard-core]39.8 KB · 72% unused
load.php[scripts:mw.config.values.wbCurrentSiteDetails]14.9 KB · 0% unused
load.php[scripts:ext.gadget.NewSection]4.8 KB · 16% unused
load.php[scripts:ext.uls.rewrite.entrypoints]1.8 KB · 33% unused
6 more files13.4 KB · 37% unused
Unused shareunder 40%40 to 70%over 70%Click a bundle marked ⤢ to see its modules.

Where the unused bytes live

first-party regex .*wikidata.*
JS unused
First 1.4 MBThird 0 b
CSS unused
First 664.3 KBThird 0 b

JavaScript files

showing 12 of 12 URLs (from 14 scripts), sorted by unused bytes
URLTotalUsedUnusedUnused %
load.php[scripts:ext.centralNotice.choiceData]1.5 MB743.4 KB776.7 KB
51.1%
62 modules in this bundle, by unused bytes
ModuleVersionTotalUsedUnusedUnused %
oojs-ui-core1vstr186.9 KB35.9 KB151.0 KB
80.8%
ext.discussionTools.initecnlr267.3 KB150.6 KB116.6 KB
43.6%
jqueryxt2am137.4 KB56.6 KB80.8 KB
58.8%
moment1123x97.2 KB24.1 KB73.1 KB
75.2%
ext.wikimediaEventso25cw79.0 KB22.3 KB56.7 KB
71.7%
skins.vector.jso4un860.6 KB24.7 KB35.9 KB
59.2%
oojs-ui-windows1fwp553.4 KB18.4 KB35.0 KB
65.6%
mediawiki.api2utky27.0 KB4.9 KB22.2 KB
82.0%
ext.uls.interfacei6zf447.2 KB25.6 KB21.5 KB
45.7%
ext.centralNotice.display1jbsp30.5 KB9.1 KB21.4 KB
70.2%
ext.testKitchen3b3oj30.7 KB17.0 KB13.7 KB
44.6%
jquery.i18n1em9733.6 KB21.9 KB11.7 KB
34.9%
oojs1u2cw15.0 KB3.6 KB11.3 KB
75.7%
mediawiki.util9btvw16.3 KB6.7 KB9.6 KB
58.9%
mediawiki.page.readya16sl16.5 KB6.9 KB9.6 KB
58.0%
ext.navigationTiming1u0am10.8 KB1.4 KB9.3 KB
86.6%
mediawiki.jqueryMsgx6c1g29.8 KB21.5 KB8.3 KB
28.0%
mmv.bootstraph6pct25.6 KB18.8 KB6.8 KB
26.5%
mediawiki.page.watch.ajaxiqjcb8.9 KB2.5 KB6.3 KB
71.6%
ext.centralNotice.kvStorec4zi36.8 KB1.1 KB5.7 KB
83.6%
jquery.textSelection1x0f05.8 KB287 B5.6 KB
95.2%
ext.eventLogging.metricsPlatform1jqfq16.6 KB11.1 KB5.5 KB
32.9%
mediawiki.Titlef7e8e10.2 KB6.1 KB4.1 KB
40.1%
skins.vector.clientPreferences1yzp313.6 KB9.5 KB4.1 KB
29.9%
ext.wikimediaEvents.testKitchen16e4i4.6 KB785 B3.9 KB
83.4%
mediawiki.base1mrcd26.0 KB22.2 KB3.7 KB
14.4%
ext.eventLogging13btz29.6 KB25.9 KB3.7 KB
12.5%
rangefixmtvel3.9 KB347 B3.6 KB
91.3%
mediawiki.language10erv8.7 KB5.1 KB3.5 KB
40.8%
jquery.uls.data1150b42.8 KB39.4 KB3.3 KB
7.8%
ext.wikimediaEvents.wikibase1r3lq3.2 KB426 B2.8 KB
86.9%
ext.urlShortener.toolbaryecdv3.8 KB1.1 KB2.7 KB
70.9%
mediawiki.userdaofm4.2 KB1.7 KB2.5 KB
58.8%
ext.checkUser.clientHints13jk23.0 KB635 B2.4 KB
79.3%
ext.centralNotice.impressionDietvfmsr2.7 KB446 B2.3 KB
83.9%
mediawiki.String1xuwk2.4 KB543 B1.9 KB
78.0%
mediawiki.routernss952.4 KB761 B1.7 KB
69.3%
mediawiki.page.galleryuihx04.4 KB2.8 KB1.6 KB
35.8%
jquery.client5k8ja3.3 KB1.9 KB1.5 KB
43.8%
ext.uls.webfonts86xg22.0 KB663 B1.4 KB
67.8%
mediawiki.libs.pluralruleparser11fhr3.6 KB2.3 KB1.3 KB
35.5%
ext.uls.common1h4lr5.4 KB4.2 KB1.2 KB
22.5%
ext.centralNotice.startUpei35p2.7 KB1.5 KB1.1 KB
42.4%
mediawiki.visibleTimeout40nxy1.5 KB434 B1.1 KB
71.5%
ext.uls.compactlinksx7kik31.1 KB30.3 KB839 B
2.6%
mediawiki.storage3elpb2.9 KB2.2 KB727 B
24.2%
ext.centralNotice.geoIPwookz1.5 KB850 B698 B
45.1%
mediawiki.cookie192y93.2 KB2.6 KB620 B
18.7%
ext.uls.preferences1i0ug1.1 KB645 B445 B
40.8%
ext.centralauth.centralautologin9ixrj1.3 KB962 B325 B
25.3%
wikibase.client.vector-2022tunx01.9 KB1.6 KB256 B
13.3%
ext.echo.centralauthw08f7340 B220 B120 B
35.3%
wikibase.databox.fromWikidataqmair709 B640 B69 B
9.7%
mediawiki.experiments15xww780 B756 B24 B
3.1%
mediawiki.cldr100c7350 B342 B8 B
2.3%
ext.centralNotice.choiceData1rvvy1.2 KB1.2 KB4 B
0.3%
ext.discussionTools.minervaicons1mog8876 B876 B0 b
0.0%
site4jtht1.1 KB1.1 KB0 b
0.0%
mediawiki.editfont.stylesl9cd21003 B1003 B0 b
0.0%
mmv.codex1inu869.8 KB69.8 KB0 b
0.0%
oojs-ui-windows.iconsner0y1.2 KB1.2 KB0 b
0.0%
skins.vector.icons.jspoepj13.2 KB13.2 KB0 b
0.0%
load.php[scripts:@wikimedia/codex]515.5 KB217.5 KB298.0 KB
57.8%
3 modules in this bundle, by unused bytes
ModuleVersionTotalUsedUnusedUnused %
(preamble)189.5 KB31.0 KB158.4 KB
83.6%
vuew4s4t156.2 KB16.6 KB139.5 KB
89.4%
codex-styles1mkfc169.9 KB169.9 KB0 b
0.0%
load.php[scripts:jquery.chosen]388.6 KB103.9 KB284.8 KB
73.3%
2 modules in this bundle, by unused bytes
ModuleVersionTotalUsedUnusedUnused %
jquery.uimy4cu344.6 KB90.1 KB254.4 KB
73.8%
jquery.chosen1r8g044.1 KB13.7 KB30.4 KB
68.8%
load.php[scripts:ext.visualEditor.core.utils.parsing]60.5 KB14.3 KB46.2 KB
76.4%
8 modules in this bundle, by unused bytes
ModuleVersionTotalUsedUnusedUnused %
ext.visualEditor.desktopArticleTarget.initicod331.2 KB8.9 KB22.3 KB
71.5%
ext.visualEditor.targetLoader5li6x21.8 KB2.2 KB19.5 KB
89.7%
ext.visualEditor.core.utils.parsingpxlsz3.3 KB800 B2.5 KB
76.5%
ext.visualEditor.tempWikitextEditorWidgetbm2az1.5 KB770 B790 B
50.6%
ext.visualEditor.progressBarWidgetbno9f1.3 KB726 B627 B
46.3%
ext.visualEditor.vefb3kh303 B124 B179 B
59.1%
ext.visualEditor.supportCheck1ogmv721 B611 B110 B
15.3%
ext.visualEditor.track10mz7295 B192 B103 B
34.9%
load.php[scripts:ext.gadget.formWizard-core]39.8 KB11.2 KB28.7 KB
71.9%
1 module in this bundle, by unused bytes
ModuleVersionTotalUsedUnusedUnused %
ext.gadget.formWizard-coreh9q3a39.8 KB11.2 KB28.7 KB
71.9%
load.php[scripts:mediawiki.action.view.postEdit]75.4 KB65.9 KB9.6 KB
12.7%
4 modules in this bundle, by unused bytes
ModuleVersionTotalUsedUnusedUnused %
mediawiki.notification1oq098.4 KB3.7 KB4.7 KB
56.2%
mediawiki.action.view.postEdit15jh74.3 KB1.6 KB2.7 KB
62.5%
mediawiki.tempUserCreatedptven3.0 KB936 B2.1 KB
69.9%
oojs-ui.styles.icons-interactionsdfnai59.7 KB59.7 KB0 b
0.0%
load.php[startup]69.2 KB63.2 KB6.0 KB
8.7%
load.php[scripts:ext.gadget.NewSection]4.8 KB4.0 KB779 B
15.9%
4 modules in this bundle, by unused bytes
ModuleVersionTotalUsedUnusedUnused %
ext.gadget.ProtectionIndicatorsr5iss3.1 KB2.5 KB596 B
19.1%
ext.gadget.NewSectionceiib409 B264 B145 B
35.5%
ext.gadget.formWizard1t6qd282 B244 B38 B
13.5%
ext.gadget.imagelinks1ois21.1 KB1.1 KB0 b
0.0%
load.php[scripts:ext.uls.rewrite.entrypoints]1.8 KB1.2 KB607 B
32.7%
1 module in this bundle, by unused bytes
ModuleVersionTotalUsedUnusedUnused %
ext.uls.rewrite.entrypoints15r141.8 KB1.2 KB607 B
32.7%
(inline) 3 scripts6.1 KB5.9 KB188 B
3.0%
https://www.wikidata.org/wiki/Special:CentralAutoLogin/start?useformat=desktop&type=script&usesul3=1254 B155 B99 B
39.0%
load.php[scripts:mw.config.values.wbCurrentSiteDetails]14.9 KB14.9 KB0 b
0.0%
3 modules in this bundle, by unused bytes
ModuleVersionTotalUsedUnusedUnused %
mw.config.values.wbCurrentSiteDetails8iazq341 B341 B0 b
0.0%
mw.config.values.wbRepo18lj4211 B211 B0 b
0.0%
oojs-ui.styles.icons-editing-core1mxvb14.4 KB14.4 KB0 b
0.0%

CSS files

showing 6 of 6 URLs (from 8 stylesheets), sorted by unused bytes
URLTotalUsedUnusedUnused %
(inline stylesheet) 3 stylesheets392.7 KB15.9 KB376.8 KB
95.9%
load.php[styles:ext.discussionTools.init.styles]318.3 KB35.4 KB282.8 KB
88.9%
load.php[styles:site.styles]4.5 KB279 B4.3 KB
94.0%
TemplateStyles:r1817813665636 B434 B202 B
31.8%
TemplateStyles:r2203837313897 B798 B99 B
11.0%
TemplateStyles:r22043327251.0 KB954 B91 B
8.7%

What to do about unused bytes

one iteration is a sample, not a verdict

A high unused-% on one run means this iteration loaded code that didn't get exercised, typical on first-load journeys before any user interaction. Drive the real flow by passing a navigation script as the input instead of a plain URL, with clicks and form fills placed between measure.start() and measure.stop(); anything in that window counts toward "used". The advice below is for code that's still unused after a representative run.

JavaScript

  • Route-split and lazy-load below-the-fold features with dynamic import(). Bundlers turn the import boundary into a separate chunk.
  • Audit big bundles for dead exports, legacy polyfills, and feature flags that no longer ship; most modern bundlers tree-shake but only when imports are precise.
  • Question third-party scripts. Tag managers, analytics SDKs and A/B test loaders often ship far more than the page uses and dominate the third-party column above.
  • Move non-critical scripts to defer or async so the parser doesn't block on code the page doesn't need yet.

CSS

  • Strip selectors no shipped HTML matches: PurgeCSS, build-time scoping in your component framework, or your CSS-in-JS extractor.
  • Drop legacy browser fallbacks if your target floor has moved (vendor prefixes, IE hacks, old flexbox syntax).
  • Split route- or component-specific CSS so the home page doesn't carry the checkout's styles.
  • Inline the critical-path CSS (above-the-fold) and lazy-load the rest with media= tricks or rel="preload" swaps.

CPU

Long tasks

Tasks ≥ 50 ms blocking the main thread, collected via the Long Task API.

TBT29 ms
Max potential input delay79 ms
Total long tasks2
Total time251 ms
Last task at1.509 s
Before first paint172 ms1 task
Before FCP172 ms1 task
Before LCP251 ms2 tasks
After load0 ms0 tasks

Long Animation Frames

A long animation frame (LOAF) is a frame that took ≥ 50 ms from input to the next paint. The part beyond the threshold is blocking time, the number that hurts Interaction to Next Paint and Total Blocking Time. Break long tasks up (scheduler.yield(), smaller chunks) or move the work off the main thread. Read more about the Long Animation Frames API.

Long animation frames3every frame ≥ 50 ms
Blocking time168.1 msacross all long frames — what hurts INP and TBT
Blocking before LCP168.1 msdelaying the largest paint — fix these first

What to fix first

ScriptFramesTime runningBlocking (share by run time)Forced style & layoutTriggered by
load.php[startup]2118.6 ms46.7 mstimer or animation callback
load.php[scripts:ext.centralNotice.choiceData]110.6 ms6 mstimer or animation callback

A frame's blocking time is split between its scripts by their share of the frame's work, capped at each script's own run time — blocking from work no script owns (HTML parsing, browser internals) stays unattributed. The per-script blocking view below uses the same attribution.

Long animation frame #1 · 373.4 msat 416.3 ms · before LCP
blocking 115.3 ms
  • Scripts & other work373.2 ms
  • Animation callbacks0.2 ms
  • Style & layout0 ms
  • Render0 ms

The browser did not report which script was responsible for this frame — typically its own style/layout work, or a cross-origin script it will not name.

Long animation frame #2 · 98.5 msat 1.490 s · before LCP
blocking 39.6 ms
  • Scripts & other work19.5 ms
  • Animation callbacks52.1 ms
  • Style & layout26.9 ms
  • Render0 ms
3 scripts ran during this frame
Ran for
10.6 ms
Started by
TimerHandler:setTimeout
How it started
timer or animation callback
Position in source
character 642560 into the file (locate it via DevTools → Performance → the Long Animation Frames track)
Ran for
8.3 ms
Started by
IdleRequestCallback
How it started
timer or animation callback
Source function
doPropagation
Position in source
character 4314 into the file (locate it via DevTools → Performance → the Long Animation Frames track)
Ran for
51.3 ms
Started by
FrameRequestCallback
How it started
timer or animation callback
Source function
flushCssBuffer
Position in source
character 3240 into the file (locate it via DevTools → Performance → the Long Animation Frames track)
Long animation frame #3 · 75.9 msat 1.405 s · before LCP
blocking 13.2 ms
  • Scripts & other work59.7 ms
  • Animation callbacks12 ms
  • Style & layout4.2 ms
  • Render0 ms
2 scripts ran during this frame
Ran for
47 ms
Started by
IdleRequestCallback
How it started
timer or animation callback
Source function
doPropagation
Position in source
character 4314 into the file (locate it via DevTools → Performance → the Long Animation Frames track)
Ran for
12 ms
Started by
FrameRequestCallback
How it started
timer or animation callback
Source function
flushCssBuffer
Position in source
character 3240 into the file (locate it via DevTools → Performance → the Long Animation Frames track)

Blocking time per script (browser-reported)

How much each script blocked the main thread, derived from the Long Animation Frame API. Each frame's blocking time is split between its scripts by their share of the frame's work, capped at each script's own run time — blocking from work no script owns (HTML parsing, browser internals) is not attributed (older data credits the script that started the frame). The closest answer to "which script should I fix to improve TBT" the platform exposes.

Top scripts blocking the main thread

2 of 2 scripts
load.php[startup]
47 ms · 4 frames · worst 29 ms

Blocking time per script (trace)

Total Blocking Time attributed per script from the Chrome trace: every main-thread task longer than 50 ms blocks input for the remainder, and each blocking task is credited to the script whose own code ran the longest during that task.

TBT152.3 ms
Blocking tasks2
TBT before LCP152.3 ms2 tasks

What kind of work blocked

mostly style & layout · 152 ms total
Style & layout124.8 ms82.0%
Running JavaScript19.1 ms12.5%
Paint & composite4.6 ms3.0%
Other browser work3.4 ms2.2%
Parsing HTML & CSS0.3 ms0.2%
Style & layout (82%): usually a large DOM, expensive CSS selectors or JavaScript forcing synchronous layout. See Forced reflows · Slowest CSS selectors (Rendering tab) · Style invalidations (Rendering tab)
Running JavaScript (13%): the scripts responsible are listed right below. See Slowest JS functions · Timers

Top scripts blocking the main thread

2 of 2 scripts
Browser's own work (no script responsible)
123 ms · 1 task
load.php[startup]
30 ms · 1 task

Where the time went

All main-thread work during the full page load, not just the share that blocked input. Calculated from the Chrome trace.

Categories

694 ms total
Running JavaScript293 ms42.2%
Style & layout232 ms33.4%
Other browser work (scheduling)97 ms14.0%
Parsing HTML & CSS28 ms4.0%
Paint & composite28 ms4.0%
Garbage collection10 ms1.4%
Parsing & compiling JavaScript6 ms0.9%
What do these categories mean?
Parsing HTML & CSSparseHTML
Reading the HTML and CSS and building the page structure. Grows with document size — a big server-rendered page costs more here.
Style & layoutstyleLayout
Working out which CSS rules apply and where every element goes on the page. Grows with DOM size and selector complexity.
Parsing & compiling JavaScriptscriptParseCompile
Parsing and compiling JavaScript before it can run — the cost of shipping bytes of JS, even unused ones.
Running JavaScriptscriptEvaluation
Running JavaScript: event handlers, timers, promise callbacks and script execution.
Paint & compositepaintCompositeRender
Painting pixels and assembling layers into the frames you see on screen.
Garbage collectiongarbageCollection
Reclaiming memory JavaScript no longer uses. A lot of it means allocation-heavy code.
Other browser work (scheduling)other
Chrome’s own task management: per-task overhead and thousands of sub-millisecond scheduler ticks — not page work you can attribute or optimize away. On this page 96 ms of it is this per-task bookkeeping (RunTask self time in the trace).

CPU time per script

Scripts by main-thread time

2 of 2 scripts

CPU time per moduleProfile run

Main-thread CPU time attributed to the individual modules inside concatenated JavaScript bundles (MediaWiki ResourceLoader), so a heavy bundle can be traced to the modules that actually cost the time.

The data comes from the extra profile run, not from the timed iterations.

ModuleVersionSelf time
jqueryxt2am67.1 ms
mediawiki.page.galleryuihx08.8 ms
ext.wikimediaEventso25cw1.4 ms
mediawiki.storage3elpb1.3 ms
ext.centralNotice.startUpei35p0.6 ms
ext.navigationTiming1u0am0.5 ms
skins.vector.jso4un80.3 ms
ext.testKitchen3b3oj0.2 ms
ext.eventLogging13btz0.1 ms
(rest of the bundle, not tied to one module)36.7 ms
ModuleVersionSelf time
mediawiki.notification1oq090.5 ms
(rest of the bundle, not tied to one module)1.1 ms
ModuleVersionSelf time
ext.visualEditor.supportCheck1ogmv0.1 ms
(rest of the bundle, not tied to one module)1.3 ms

Slowest JS functions

The functions where main-thread JavaScript time was actually spent, sampled by Chrome's JavaScript profiler. Self time is spent in the function itself; total time includes the functions it called. For loader/dispatcher functions whose total dwarfs their self time, the runs line shows the top functions and modules (up to five, ≥ 1 ms) the total was actually spent running.

Functions by self time

15 of 42 functions
FunctionWhereSelf timeTotal time
CompactInterlanguageList.hideOriginalload.php[scripts:ext.centralNotice.choiceData]35.6 ms35.6 ms
flushWrites
runs: load.php[startup] (3.1 ms)
load.php[startup]23.8 ms27.0 ms
runScript
runs: load.php[scripts:ext.centralNotice.choiceData] (67.3 ms), load.php[scripts:jquery.chosen] (16.3 ms)
load.php[startup]16.4 ms152.6 ms
insertBeforeBrowser internal (not your code)13.1 ms13.1 ms
getClientRectsBrowser internal (not your code)9.0 ms9.0 ms
setTimeoutBrowser internal (not your code)8.5 ms8.5 ms
require
runs: load.php[scripts:ext.centralNotice.choiceData] (29.0 ms), load.php[scripts:@wikimedia/codex] (5.3 ms)
load.php[startup]8.0 ms26.8 ms
appendChildBrowser internal (not your code)6.0 ms6.7 ms
implload.php[startup]5.2 ms7.3 ms
requestIdleCallbackBrowser internal (not your code)4.1 ms4.1 ms
doPropagation
runs: load.php[startup] (62.8 ms), load.php[scripts:ext.centralNotice.choiceData] (1.9 ms)
load.php[startup]4.1 ms69.8 ms
resources/lib/vue/vue.js
runs: load.php[scripts:@wikimedia/codex] (2.0 ms)
load.php[scripts:@wikimedia/codex]3.3 ms5.3 ms
querySelectorAllBrowser internal (not your code)3.1 ms3.1 ms
updateTooltipOnElementload.php[scripts:ext.centralNotice.choiceData]3.0 ms4.0 ms
(anonymous)load.php[scripts:ext.centralNotice.choiceData]2.9 ms3.3 ms

TimersProfile run

How much setTimeout/setInterval work the page runs, credited to the script that scheduled each timer. Many zero-delay timers mean work sliced into a machine-gun of tiny tasks; repeating timers are polling.

Timers set59
Times fired56
Fire time92.6 ms
Zero-delay timers53
Repeating timers0
Zero-delay slicing: jquery split work into 50 back-to-back tasks costing 72 ms. Consider batching the work or moving it to requestIdleCallback or a worker.

Timer cost by script

2 scripts
load.php[startup]
57 ms · set 1 time · fired 23 times
load.php[scripts:ext.centralNotice.choiceData]
36 ms · set 58 times · fired 33 times

The timers, by where they were set

top 9 by fire time
Set byDelayTypeTimes setTimes firedFire time
jquery0 msonce505071.6 ms
mediawiki.page.gallery0 msonce1118.8 ms
SafeStorage in mediawiki.storage2000 msonce220.7 ms
jquery0 msonce110.7 ms
ext.navigationTiming0 msonce110.6 ms
requestUpdate in load.php[startup]:222000 msonce110.2 ms
BackgroundQueue.queue.add in ext.eventLogging30000 msonce100.0 ms
run in ext.wikimediaEvents60000 msonce100.0 ms
setActive in ext.wikimediaEvents100000 msonce100.0 ms

Forced reflows

A forced reflow happens when JavaScript reads a layout-triggering property (offsetTop, getBoundingClientRect, …) inside a handler, forcing the browser to synchronously recompute layout. The scripts below caused most of the page's reflows. Fix them in priority order.

Scripts causing reflows

1 reflow ≥ 2 ms across 1 script
load.php[startup]
9 ms · 1 reflow · worst 9 ms

First vs third party CPU time

Main-thread CPU time from the Chrome trace split by domain. First party is wikidata.org.

First party285 ms
Third party0 ms
Domains1

Want to dig deeper? Download the Chrome trace and drag-and-drop it into Performance in DevTools.