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.
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 shown135
Partial29
Dropped3
Effective FPS56.5
Longest gap116 msat 446 ms
Why was rendering delayed?
Rendering was not meaningfully delayed. First paint landed at 452 ms on a 196 ms first byte; the 3 render-blocking requests were done by 271 ms and the remaining ~181 ms is style and layout work (15 ms of it measured style recalculation and forced reflows). The largest paint followed at 692 ms.
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).
Style recalculation is not holding up your paint. 14 ms of restyling before the page painted, 3.1 % of the time to First Contentful Paint. Nothing here needs attention.
Before first contentful paint
Recalculations8
Elements126
Total time13.899 ms
Largest recalculation97 elements · 8.584 ms
Before largest contentful paint
Recalculations31
Elements937
Total time101.118 ms
Largest recalculation448 elements · 48.877 ms
The recalculation work before first paint is 3.1 % of the time to First Contentful Paint.
Forced reflows before the page painted
measured by Chrome during this run
JavaScript read a layout value (offsetTop, getBoundingClientRect, …) while the page was mid-change, so the browser had to re-layout synchronously, work that blocks rendering. Reflows before First Contentful Paint delayed the first pixels; reflows before Largest Contentful Paint delayed the main content.
Forced reflows before FCP10
Time spent in forced reflows before FCP1.3 ms
Forced reflows before LCP39
Time spent in forced reflows before LCP67 ms
That is 9.7 % of the time to Largest Contentful Paint. The number of reflows matters more than the milliseconds: layout thrashing multiplies on slower devices.
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. Web fonts are context, not blockers: text renders invisible or in a fallback face while they load, so a font finishing after a paint is the classic reason text changed late.
web font · www.antikeo.com · finished after first paint
loaded after LCP, at 2.224 s
16.2 KB
23 ms
0173 ms346 ms519 msFCP 452 msLCP 692 ms
Style invalidations
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. 722 style recalculations and 3 907 layout invalidations fired after first paint, on a page the user was already looking at. The biggest driver is pseudo valid (58×). Start with the script under "Scripts causing invalidations" that keeps triggering it.
Style recalculations763722 after first paint
Layout invalidations4 0403 907 after first paint
Changes that keep invalidating
top 15
pseudo: valid58×
pseudo: invalid58×
attribute: class34×
attribute: data-original-title16×
attribute: title16×
attribute: tabindex8×
class: lazyloading8×
attribute: src7×
pseudo: disabled4×
pseudo: enabled4×
class: lazyload4×
class: lazyloaded4×
pseudo: hover2×
class: slick-arrow2×
class: slick-hidden2×
Invalidation reasons
split at first paint
Between first and largest paint
Invalidations while the largest paint was still pending, so these delayed it.
Reason
Style recalculations
Layout
An animation updated stylesAnimate transform and opacity so the compositor can run it off the main thread.
2
–
A node was inserted into the page
56
–
Related style rule
2
–
JavaScript changed an inline styleSet a class instead of writing element.style, so the browser can batch the work.
19
–
A stylesheet rule changed
31
–
A pseudo-class state changed (:hover, :focus, …)
1
–
A web font finished loadingPreload the font or use font-display so a late swap does not re-style the page.
–
1 619
An element entered layout
–
1 121
A style change forced layout
–
17
An element left layout
–
23
An element's size changed
–
21
Unknown
–
21
An SVG element changed
–
5
Scrollbar changed
–
1
After the largest paint
Churn on the fully rendered page: wasted work and possible jank, but no paint delay.
Reason
Style recalculations
Layout
An animation updated stylesAnimate transform and opacity so the compositor can run it off the main thread.
288
–
A node was inserted into the page
66
–
Related style rule
126
–
JavaScript changed an inline styleSet a class instead of writing element.style, so the browser can batch the work.
73
–
An @keyframes rule changed
41
–
A stylesheet rule changed
5
–
Frame
9
–
A pseudo-class state changed (:hover, :focus, …)
1
–
Attribute
2
–
A web font finished loadingPreload the font or use font-display so a late swap does not re-style the page.
–
267
An element entered layout
–
383
A style change forced layout
–
329
An element left layout
–
72
An element's size changed
–
11
Unknown
–
9
An SVG element changed
–
4
Scrollbar changed
–
3
Child anonymous block changed
–
1
Before first paint: building the page
The page being constructed and styled for the first render. Expected work, shown for scale.
33 animations run on the main thread instead of on the browser's fast path that animates without blocking other page work (the compositor); they can make the rendering you see above janky. See them on the CPU tab.
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.
warn(0)Don't scale images in the browseravoidScalingImages
The page has 10 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.
infoAdd decoding="async" to non-critical imagesdecodingAsync
The page has 64 images (out of 64) 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
The page has 44 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
The page has 9 CPU long tasks with the total of 829 ms. The total blocking time is 379 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
self
self
cross-origin-descendant
cross-origin-descendant
self
self
self
self
self
warn(0)Serve images in modern formats (AVIF, WebP)modernImageFormats
The page ships 7 images (out of 7) 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
warn(0)Avoid extra requests by setting cache headerscacheHeaders
The page has 11 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 52.4 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.
The page has 13 font requests. Do you really need them? What value does the fonts give the user?
How many fonts do you need on a page for the user to get the message? Fonts can slow down the rendering of content, try to avoid loading too many of them because worst case it can make the text invisible until they are loaded (FOIT—flash of invisible text), best case they will flicker the text content when they arrive.
warn(0)Total JavaScript size shouldn't be too bigjavascriptSize
The total JavaScript transfer size is 1.4 MB and the uncompressed size is 4.7 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?
warn(0)Total page size shouldn't be too bigpageSize
The page total transfer size is 3.2 MB, which is more than the coach limit of 3 MB. That is really big and you need to make it smaller.
Avoid having pages that have a transfer size over the wire of more than 3 MB (desktop) and 2 MB (mobile) because heavy pages hurt performance and are expensive for users on metered connections. Reference: HTTP Archive median page weight in 2024 was around 2.7 MB desktop / 2.4 MB mobile, so this rule fires when a page is above the modern median.
warn(10)Don't use private headers on static contentprivateAssets
The page has 9 requests with private headers. 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.
warn(39)Avoid slowing down the critical rendering pathavoidRenderBlocking
The page has 4 blocking requests and 6 in body parser blocking (6 JavaScript and 4 CSS). There are 1 potentially render blocking requests. You need to verify if it is render blocking: https://apis.google.com/js/platform.js
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.
infoThe favicon should be small and cacheablefavicon
The favicon size is 15.3 kB bytes. That's quite big, can you make it smaller?
It is easy to make the favicon big but please avoid doing that, because every browser will then perform an unnecessarily large download. And make sure the cache headers are set for a long time for the favicon. It is easy to miss since it's another content type.
warn(50)Total image size shouldn't be too bigimageSize
The page total image size is 1.1 MB. It's really big. Is the page using the right format for the images? Can they be lazy loaded? Are they compressed as good as they can be? Make them smaller by using https://imageoptim.com/.
Avoid having too many large images on the page. The images will not affect the first paint of the page, but it will eat bandwidth for the user.
infoLong cache headers is goodcacheHeadersLong
The page has 48 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.
error(90)Avoid Frontend single point of failuresspof
The page has 1 request inside of the head that can cause a SPOF (single point of failure). Load them asynchronously or move them outside of the document head.
A page can be stopped from loading in the browser if a single JavaScript, CSS, and in some cases a font, couldn't be fetched or is loading really slowly (the white screen of death). That is a scenario you really want to avoid. Never load 3rd-party components synchronously inside of the head tag.
https://www.antikeo.com/assets/css/style-1.6.min.css?185 size is 43.8 kB (43758) 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.
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.
error(99)Avoid using incorrect mime typesmimeTypes
The page has 1 misconfigured mime type.
It's not a great idea to let browsers guess content types (content sniffing), in some cases it can actually be a security risk.
warn(0)Avoid too many third party requeststhirdParty
The page do more requests to third party domains (48 requests and 1.8 MB) then first party (31 requests and 1.5 MB). The page transfer more bytes from third party domains (1.8 MB) then first party (1.5 MB). The regex .*antikeo.* was used to calculate first/third party requests.
Do not load most of your content from third party URLs.
infoAvoid unnecessary headersunnecessaryHeaders
There are 2 responses that sets a p3p header. There are 58 responses that sets both a max-age and expires header. There are 13 responses that sets a pragma no-cache header (that is a request header). There are 3 responses that sets a x-frame-options:sameorigin header. There are 61 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.
The meta description is too long. It has 171 characters, the recommended max is 160
Use a page description to make the page more relevant to search engines.
warn(50)Page titlepageTitle
The title is too long by 2 characters. The recommended max is 60
Use a title to make the page more relevant to search engines.
warn(80)Set a sensible viewport meta tagviewport
The viewport meta tag sets maximum-scale to 1 or less, which prevents the user from zooming in. Remove it.
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
infoDo not send too long headerslongHeaders
https://www.google.c...ng/merchantverse/ has a header content-security-policy that is 1349 characters long. https://connect.face...en_US/fbevents.js has a header content-security-policy that is 1410 characters long. https://connect.face...en_US/fbevents.js has a header permissions-policy that is 874 characters long. https://connect.face...g/781787612411430 has a header content-security-policy that is 1344 characters long. https://connect.face...g/781787612411430 has a header permissions-policy that is 874 characters long.
The page embeds 2 cross-origin iframes without a sandbox attribute. Add sandbox="" with the minimum set of allow-* tokens the embed actually needs.
Adding a sandbox attribute to a cross-origin iframe restricts what the embedded page can do (script execution, form submission, top-level navigation, popups, etc.) and is one of the cheapest ways to limit the blast radius of a third-party embed. https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe#sandbox
warn(0)Declare a referrer policy on the documentreferrerPolicy
No <meta name="referrer"> tag was found on the page. Set a Referrer-Policy response header (preferred) or add a meta tag, for example <meta name="referrer" content="strict-origin-when-cross-origin">.
Without an explicit referrer policy the browser falls back to the user-agent default and may leak the full URL of the previous page (including query strings) to every cross-origin request. Set a Referrer-Policy response header (preferred) or a <meta name="referrer"> tag in the document. https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referrer-Policy
warn(0)Configure session-replay tools carefully if you use themsessionReplay
The page loads 2 session-replay scripts. Confirm input redaction is enabled, that you have explicit user consent before recording starts, and that the data-retention and storage location of the recordings match your privacy policy.
Session-replay tools (Hotjar, FullStory, Microsoft Clarity, LogRocket, Smartlook, Mouseflow and similar) record user behaviour on the page in detail. They have legitimate uses but they have also been shown to capture personally-identifiable information from form fields when not configured with redaction. If you use one of these, make sure input redaction is on, that you have explicit user consent under the relevant regulation (GDPR, CCPA, etc.) before recording starts, and that you know where the recordings are stored and for how long. https://www.princeton.edu/~jmayer/papers/Acar2018.pdf
warn(0)Avoid embedding services from surveillance capitalist companiessurveillance
The page embeds 10 resources from companies that profit from user surveillance. Consider privacy-respecting alternatives.
Embedding scripts or iframes from companies whose business model is surveillance capitalism (Google, Facebook, etc.) leaks detailed user data on every page view, often before the user has had a chance to consent. See https://en.wikipedia.org/wiki/Surveillance_capitalism for background. Prefer privacy-respecting alternatives where possible.
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
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
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
infoSet a NEL header so the browser reports network errors back to you.nelHeader
Set a NEL header (paired with Reporting-Endpoints) to collect connection-level error reports from the field.
The NEL (Network Error Logging) response header tells the browser to record connection-level failures (DNS, TLS, HTTP errors) and ship them to a reporting endpoint. NEL pairs with the Reporting-Endpoints / Report-To header — the page declares the endpoint group and NEL points at it. Together they give you visibility into errors that never reach your origin server. https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/NEL
infoDeclare reporting endpoints so the browser can deliver Reporting-API events.reportingEndpointsHeader
Set a Reporting-Endpoints header (or the legacy Report-To header) so CSP reports, NEL data and other Reporting-API events have an endpoint to land at.
The Reporting-Endpoints response header (the successor to Report-To) names the URLs that browsers should POST reports to. Without it, CSP report-to directives, Cross-Origin-Opener-Policy reports, NEL data and other Reporting-API events have nowhere to go. The legacy Report-To header is still accepted for older Chromium versions. https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Reporting-Endpoints
error(0)Set a strict transport header to make sure the user always use HTTPS.strictTransportSecurityHeader
Set a strict transport header to make sure the user always use HTTPS.
The HTTP Strict-Transport-Security response header (often abbreviated as HSTS) lets a web site tell browsers that it should only be accessed using HTTPS, instead of using HTTP. https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Strict-Transport-Security.
warn(0)Do not share user data with third parties.thirdPartyPrivacy
The page has 54% requests that are 3rd party (43 requests with a size of 1.8 MB). The page also have request to companies that harvest data from users and do not respect users privacy (see https://en.wikipedia.org/wiki/Surveillance_capitalism). The page do 21 survelliance requests and uses 4 survelliance tools. The page do 23 surveillance requests and uses 5 surveillance tools. The page do 14 utility requests and uses 3 utility tools. The page do 3 tag-manager requests and uses 1 tag-manager tool. The page do 10 social requests and uses 2 social tools. The page do 2 ad requests and uses 1 ad tool.
Using third party requests shares user information with that third party. Please avoid that! The project https://github.com/patrickhulce/third-party-web is used to categorize first/third party requests.
warn(70)Avoid third party cookies that is used to track the user.thirdPartyCookies
The page sets 3 third party cookies.
Third party cookies are used to track the user. They are automatically blocked in Safari and Firefox.
Offenders
.google.com
.google.com
ct.pinterest.com
warn(80)Use a strict Content-Security-Policy header to mitigate cross-site scripting (XSS) attacks.contentSecurityPolicyHeader
The policy declares no default-src or script-src directive, which means scripts can be loaded from anywhere. Add at least default-src so unknown directive types fall back to a safe value.
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.
TitleAntikeo | Marketplace spécialisée en Art • Antiquités • DesignThe document title, shown in the browser tab and used by search results.
Layout viewport1350 × 10505 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 elements1,750Very large, slows layout and styleTotal HTML elements. Fewer means less for the browser to style, lay out and paint.
Avg DOM depth11How deeply elements are nested on average.
Max DOM depth20The deepest nesting on the page. Deep branches cost more style recalculation.
Iframes2Embedded documents. Each is a separate page the browser loads and renders.
Script tags40Number 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 storage75 BData the page saved in localStorage, kept across visits.
Session storage9 BData kept in sessionStorage for this tab session only.
Connection type4GWhat the Network Information API reported for the test connection.
Resource hints
7 hints
preconnect
https://use.typekit.net/
https://p.typekit.net/
https://fonts.googleapis.com/
https://fonts.gstatic.com/
https://www.googletagmanager.com/
https://cdn.jsdelivr.net/
https://cdn.cookie-script.com/
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.
31 recalculations touching 937 elements (101.118 ms) — the largest touched 448 elements (48.877 ms)
DOM path
body > div:eq(4) > div > div > div > div#main-slider > div > div > div > a > div > div > div:eq(1)
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:
3 shifts add up to a 0.005 CLS. ul moved at 546 ms. 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.
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.
Tasks ≥ 50 ms blocking the main thread, collected via the Long Task API.
TBT379 ms
Max potential input delay140 ms
Total long tasks9
Total time829 ms
Last task at4.378 s
Before first paint0 ms0 tasks
Before FCP0 ms0 tasks
Before LCP82 ms1 task
After load179 ms2 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 frames15showing the 10 with the most blocking time
Blocking time419.9 msacross all long frames — what hurts INP and TBT
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 · 144.6 msat 1.221 s · before load
blocking 93.4 ms
Scripts & other work142 ms
Animation callbacks2.6 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 · 125.5 msat 1.928 s · before load
Long animation frame #7 · 69.8 msat 441.6 ms · before LCP
blocking 19.2 ms
Scripts & other work13.3 ms
Animation callbacks56.4 ms
Style & layout0.1 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 #8 · 84.5 msat 1.368 s · before load
blocking 17.6 ms
Scripts & other work81.1 ms
Animation callbacks3.1 ms
Style & layout0.3 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 #9 · 67.6 msat 4.378 s · after load
blocking 17.4 ms
Scripts & other work67 ms
Animation callbacks0.6 ms
Style & layout0 ms
Render0 ms
1 script ran during this frame · forced style & layout 0.6 ms
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.
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.
TBT397.9 ms
Blocking tasks10
TBT before LCP45.8 ms2 tasks
What kind of work blocked
mostly running javascript · 398 ms total
Running JavaScript349.0 ms87.8%
Style & layout38.2 ms9.6%
Garbage collection7.2 ms1.8%
Paint & composite1.5 ms0.4%
Other browser work1.2 ms0.3%
Parsing & compiling JavaScript0.3 ms0.1%
Parsing HTML & CSS0.3 ms0.1%
Running JavaScript (88%): the scripts responsible are listed right below. See Timers
All main-thread work during the full page load, not just the share that blocked input. Calculated from the Chrome trace.
Categories
2.224 s total
Running JavaScript1.405 s63.2%
Style & layout341 ms15.3%
Other browser work (scheduling)217 ms9.8%
Paint & composite137 ms6.2%
Parsing HTML & CSS85 ms3.8%
Garbage collection28 ms1.3%
Parsing & compiling JavaScript11 ms0.5%
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 214 ms of it is this per-task bookkeeping (RunTask self time in the trace).
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 set263
Times fired244
Fire time292.2 ms
Zero-delay timers193
Repeating timers4
Zero-delay slicing: kd in https://www.googletagmanager.com/gtm.js?id=GTM-PGPNSX6 split work into 66 back-to-back tasks costing 95 ms. Consider batching the work or moving it to requestIdleCallback or a worker.
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.
Each long animation frame reports how much time each script spent forcing synchronous style and layout, i.e. JavaScript reading layout-triggering properties mid-execution. Same actionable answer as forced reflows above but measured directly by the browser instead of inferred from the trace.
Main-thread CPU time from the Chrome trace split by domain. First party is antikeo.com.
First party225 ms
Third party1.172 s
Domains9
CPU time per domain/tool
Domain / tool breakdown
9 entities
Google Tag Manager
439.9 ms
Google CDN
303.4 ms
www.antikeo.com
227.1 ms
Facebook
158.7 ms
Other Google APIs/SDKs
126.8 ms
Clarity
73.0 ms
Cookie-Script.com
37.0 ms
Pinterest
33.1 ms
Bing Ads
17.1 ms
Non-composited animations
Animations that fell back from the compositor to the main thread, blocking each frame instead of running on the GPU.
Each chip below is a CSS property the page tried to animate that Chrome couldn't hand to the compositor. Swap it for a transform or opacity equivalent where you can.
Properties to fix
10 properties · 33 animations
color5×
font-weight3×
padding-left3×
padding-right3×
padding-top3×
font-size3×
border-bottom-left-radius3×
border-bottom-right-radius3×
padding-bottom3×
visibility1×
Want to dig deeper? Download the Chrome trace and drag-and-drop it into Performance in DevTools.
Domains that didn't match any tool in Third party web. If you are sure they are third party domains, please do a PR to that project. You can also fine tune the list using --firstParty.
bat.bing.net
Third party cookies2
.google.com1 cookie
NID
ct.pinterest.com1 cookie
_pinterest_ct_ua
First party vs third party
31 first · 48 third party
Transfer size3.1 MB
First party1.4 MB45.2%
Third party1.7 MB54.8%
Content size6.9 MB
First party2.3 MB33.6%
Third party4.6 MB66.4%
Requests79
First party3139.2%
Third party4860.8%
First party requests and sizes per content type
31 requests
Calculated using .*antikeo.* (use --firstParty to configure).
Content
Header Size
Transfer Size
Content Size
Requests
html
0 b
51.6 KB
381.4 KB
1
css
0 b
85.5 KB
471.0 KB
9
javascript
0 b
116.4 KB
371.8 KB
6
image
0 b
1.0 MB
1.0 MB
8
font
0 b
80.1 KB
79.2 KB
5
favicon
0 b
14.9 KB
14.7 KB
1
other
0 b
896 B
461 B
1
Total
N/A
1.4 MB
2.3 MB
31
Third party requests and sizes per content type
48 requests
Content
Header Size
Transfer Size
Content Size
Requests
html
0 b
10.7 KB
61.3 KB
3
css
0 b
2.1 KB
10.7 KB
2
javascript
273 B
1.3 MB
4.1 MB
22
image
0 b
582 B
105 B
3
font
0 b
402.7 KB
401.8 KB
8
favicon
0 b
0 b
0 b
0
json
0 b
1.0 KB
651 B
2
plain
837 B
828 B
0 b
8
Total
1.0 KB
1.7 MB
4.6 MB
48
Axe
Axe is an accessibility testing engine for websites and other HTML-based user interfaces. Tested using axe-core version 4.11.4. Read more about axe-core.
Fix any of the following:
Element has insufficient color contrast of 4.35 (foreground color: #ffffff, background color: #6a7b8b, font size: 10.5pt (14px), font weight: normal). Expected contrast ratio of 4.5:1
Fix any of the following:
Element has no title attribute
aria-label attribute does not exist or is empty
aria-labelledby attribute does not exist, references elements that do not exist or references elements that are empty
Element's default semantics were not overridden with role="none" or role="presentation"
<p class="description" data-animation="fadeInUp" data-delay="0.5s" style="color: rgb(255, 255, 255); animation-delay: 0.5s;">Antikeo transforme la rentrée en art de vivre studieux, élégant et inspirant.</p>
