Run 1 summary

https://www.mediawiki.org/wiki/How_to_contribute

Tested 2026-05-26 04:40:13 using Firefox 150.0.2 (runtime settings)

SummaryWaterfall MetricsVideoFilmstrip CoachPageXrayCPU Screenshots

Summary

LCP859 ms
Coach89
Loading & responsiveness
TTFB
406 ms
First Paint
858 ms
Fully Loaded
1.747 s
Page weight & requests
Total transfer size
552.9 KB
Requests
27
Visual progress
First Visual Change
900 ms
Speed Index
923 ms
Visual Complete 85%
900 ms
Visual Complete 99%
1.533 s
Last Visual Change
2.033 s
Screenshot
Waterfall | Download HAR | 

Waterfall

First paintFCPLCPDOMContentLoadedDOM interactiveLoadRender-blockingRedirectError

Video

Run 1
Download video

Filmstrip

12 frames

Use --filmstrip.showAll to show all filmstrips.

0 s
0.9 sFirst Contentful Paint 859 msLCP <DIV> 859 msmwStartup 867 msDOM Content Loaded Time 872 msFirst Visual Change 900 msVisual Complete 85% 900 msVisual Complete 95% 900 msHeading 900 ms
1 sLargest Image 933 ms
1.1 s
1.2 s
1.5 sPage Load Time 1.434 s
1.6 sVisual Complete 99% 1.533 s
1.7 s
1.8 sFully Loaded 1.747 s
1.9 s
2 s
2.1 sLast Visual Change 2.033 s
Performance advice | Best practice advice | Privacy advice | Page info | Technologies | 

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

89
8 warnings3 info
warn(0)Serve images in modern formats (AVIF, WebP)modernImageFormats

The page ships 10 images (out of 10) 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 12 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 25.5 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(29)Lazy-load below-the-fold imageslazyLoadingImages

The page has 5 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(50)Total JavaScript size shouldn't be too bigjavascriptSize

The total JavaScript transfer size is 450.4 kB. This is quite large.

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.mediawiki.org/w/load.php?lang=en&modules=startup&only=scripts&raw=1&skin=vector-202220.7 KB0 b
https://www.mediawiki.org/w/load.php...ki.org/w/load.php17.8 KB0 b
https://www.mediawiki.org/w/load.php...ki.org/w/load.php369.3 KB0 b
https://www.mediawiki.org/w/load.php...ki.org/w/load.php2.9 KB0 b
https://www.mediawiki.org/w/load.php...ki.org/w/load.php8.9 KB0 b
https://www.mediawiki.org/w/load.php...ki.org/w/load.php18.7 KB0 b
https://auth.wikimedia.org/metawiki/wiki/Special:CentralAutoLogin/checkLoggedIn...gin/checkLoggedIn1.6 KB0 b
infoAdd decoding="async" to non-critical imagesdecodingAsync

The page has 4 images (out of 14) 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
warn(90)Don't scale images in the browseravoidScalingImages

The page has 1 image 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(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
infoLong cache headers is goodcacheHeadersLong

The page has 10 requests that have a shorter cache time than one year (but still a cache time).

Setting a cache header is good. Setting a long cache header (a year) is even better because the asset will stay in the browser cache across visits. For content-hashed URLs (e.g. app.4af2.css) you can safely use Cache-Control: max-age=31536000, immutable. For unversioned URLs that may change, use a revalidating strategy instead.

Offenders
infoMake each CSS response smalloptimalCssSize

https://www.mediawiki.org/w/load.php?lang=en&modules=ext.discussionTools.init.styles%7Cext.translate%7Cext.translate.edit.documentation.styles%7Cext.translate.tag.languages%7Cext.uls.pt%7Cext.visualEditor.desktopArticleTarget.noscript%7Cext.wikimediamessages.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&only=styles&skin=vector-2022 size is 36.4 kB (36423) 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.mediawiki.org/w/load.php...ki.org/w/load.php35.6 KB0 b
warn(95)Avoid slowing down the critical rendering pathavoidRenderBlocking

The style https://www.mediawiki.org/w/load.php?lang=en&modules=ext.discussionTools.init.styles%7Cext.translate%7Cext.translate.edit.documentation.styles%7Cext.translate.tag.languages%7Cext.uls.pt%7Cext.visualEditor.desktopArticleTarget.noscript%7Cext.wikimediamessages.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&only=styles&skin=vector-2022 is larger than the magic number TCP window size 14.5 kB. Make the file smaller and the page will render faster. The page has 1 render blocking CSS request and 0 blocking JavaScript request inside of head.

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
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.

Best practice advice

52
1 error2 warnings4 info
error(0)Cumulative Layout ShiftcumulativeLayoutShift

Layout Shift is not supported in this browser

Cumulative Layout Shift measures the sum total of all individual layout shift scores for unexpected layout shift that occur. The metric is measuring visual stability by quantify how often users experience unexpected layout shifts. It is one of Google Web Vitals.

infoGive every image a textual alternativeimageAltText

The page has 10 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
infoMeta descriptionmetaDescription

The page is missing a meta description.

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

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 41% requests to third party domains (11 requests and 24.4 kB). First party is 16 requests and 541.8 kB. The regex .*mediawiki.* was used to calculate first/third party requests.

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

infoAvoid unnecessary headersunnecessaryHeaders

There are 14 responses that sets both a max-age and expires header. There are 27 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
infoDo not send too long headerslongHeaders

https://www.mediawik...How_to_contribute has a header content-security-policy that is 4500 characters long. https://www.mediawik...ki.org/w/load.php has a header sourcemap that is 1322 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 11 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
  • .wikimedia.org NetworkProbeLimit=0.001
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

Page info

TitleHow to contribute - MediaWiki
GeneratorMediaWiki 1.47.0-wmf.3
Width1920
Height3593
DOM elements1046
Avg DOM depth12
Max DOM depth20
Iframes0
Script tags5
Local storage1.2 MB
Session storage0 b
Network Information APIunknown

Resource hints

3 hints
dns-prefetch
  • https://meta.wikimedia.org/
  • https://www.mediawiki.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
  • MediaWikiConfidence100
    Wikis
  • PHPConfidence100
    Programming languages
  • HSTSConfidence100
    Security
  • HTTP/2Confidence100
    Miscellaneous
Visual Metrics | Google Web Vitals | Largest Contentful Paint | Browser metrics | Visual Elements | Metrics from CDP | Server timings | 

Visual Metrics

Visual progress
Visual progress at 0 s0.0s
Visual progress at 1 s1.0s
Visual progress at 1.1 s1.1s
Visual progress at 1.5 s1.5s
Visual progress at 1.6 s1.6s
Visual progress at 1.8 s1.8s
Visual progress at 1.9 s1.9s
Visual progress at 2.1 s2.1s
FCP0.86s
LCP0.86s
VC850.90s
0.0s0.4s0.8s1.3s1.7s2.1s

Google Web Vitals

Largest Contentful Paint

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

859 msLCP render time

Phase breakdown

  • TTFB406 ms
  • Resource load delay0 ms
  • Resource load duration0 ms
  • Element render delay453 ms

Element

Element type
<div>
Size (w × h)
21074
Load time
0 ms

DOM path

body > div:eq(2) > div > div:eq(2) > main#content > div#bodyContent > div#mw-content-text > div:eq(1) > div:eq(1) > div:eq(1)
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.

Browser Metrics

Navigation Timing
Extra timings
User Timing marks
mwStartup867 ms

Server timings

2 entries
NameDurationDescription
cache0 mshit-front
host0 mscp3070

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 Elements3
LargestImagemediawikiwiki.svg
Display time933 ms
Position (x, y)254, 8
Size (w × h)50 × 50
HTML snippet
<img class="mw-logo-icon" src="/static/images/icons/mediawikiwiki.svg" alt="" aria-hidden="true" height="50" width="50">
Heading
Display time900 ms
Position (x, y)350, 90
Size (w × h)948 × 40
HTML snippet
<h1 id="firstHeading" class="firstHeading mw-first-heading"></h1>
LargestContentfulPaint
Display time900 ms
Position (x, y)366, 793
Size (w × h)916 × 260
HTML snippet
<div class="tech-header-intro"></div>
Summary | Largest responses | Per content type | Per domain | Expires & last-modified | 

PageXray

How the page is built.

HTTP versionHTTP/2.0
Total requests27
Total domains3
Transfer size552.9 KB
Content size0 b
Missing compression0
Cookies1711 third-party

Response codes

200
2696.3%
302
13.7%

Requests and sizes per content type

6 types
ContentHeader SizeTransfer SizeContent SizeRequests
html6.2 KB27.9 KB0 b1
css2.4 KB37.3 KB0 b2
javascript9.8 KB439.9 KB0 b7
image13.9 KB29.9 KB0 b11
favicon1005 B8.4 KB0 b1
svg4.5 KB8.4 KB0 b4
Total37.7 KB551.8 KB0 b26

Data per domain

3 domains
DomainTotal download timeTransfer SizeContent SizeRequests
www.mediawiki.org3.394 s529.1 KB0 b16
upload.wikimedia.org5.199 s22.2 KB0 b10
auth.wikimedia.org184 ms1.6 KB0 b1

Expires & last-modified statistics

typeminmedianmax
Expires0 seconds5 minutes1 year
Last modified2 hours9 weeks2 years

CPU

afterPageCompleteCheck.jpg | largestContentfulPaint.jpg | 

Screenshots