https://www.siarv.it/eventi-passati/
Tested 2026-10-20 16:24:05 using Chrome 154.0.8037.57 (runtime settings)
This page is fast to paint, snappy to interact with and visually stable, but loose on best practices and weak on user privacy.
Visual metrics
Google Web Vitals
The page has 25 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.
The page is using Google Tag Manager, this is a performance risk since non-tech users can add JavaScript to your page.
The page has 5 CPU long tasks with the total of 390 ms. The total blocking time is 126 ms and 1 long task before first contentful paint with total time of 64 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.
Timings summary
| Metric | Min | Median | Mean | Max | Runs agree? |
|---|---|---|---|---|---|
| First visual change | 400 ms | 400 ms | 411 ms | 433 ms | stable ±4% |
| Last visual change | 2.666 s | 2.700 s | 2.733 s | 2.833 s | stable ±3% |
| Speed index | 1.356 s | 1.452 s | 1.426 s | 1.470 s | stable ±4% |
| Visual readiness | 2.266 s | 2.300 s | 2.322 s | 2.400 s | stable ±3% |
| Visual complete 85 | 1.766 s | 1.900 s | 1.855 s | 1.900 s | stable ±4% |
| Visual complete 95 | 1.900 s | 2.033 s | 2.000 s | 2.066 s | stable ±4% |
| Visual complete 99 | 2.500 s | 2.500 s | 2.533 s | 2.600 s | stable ±2% |
Run 1 SpeedIndex median
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 videoUse --filmstrip.showAll to show all filmstrips.
Click a frame to seek the video to that moment. The dot marks frames where the page changed visually.
Rendering was not meaningfully delayed. First paint landed at 396 ms on a 55 ms first byte; the 9 render-blocking requests were done by 147 ms and the remaining ~249 ms is style and layout work. The largest paint followed at 1.404 s. The LCP image itself was downloaded by 787 ms; the wait was render work, not the network.
Want to see how much CSS style-recalculation work delayed FCP and LCP, plus CPU long tasks? Run with --cpu.
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.
| Request | When it loaded | Transfer | Download |
|---|---|---|---|
document | 48 ms | 23.9 KB | 46 ms |
ca29e.jsblocking | 69 ms | 158.3 KB | 69 ms |
d10d2.jsblocking | 68 ms | 82.4 KB | 68 ms |
3bcfd.cssblocking | 62 ms | 163.6 KB | 62 ms |
4476d.jsblocking | 53 ms | 37.7 KB | 53 ms |
9a399.jsblocking | 49 ms | 31.0 KB | 49 ms |
9512b.jsblocking | 35 ms | 10.7 KB | 35 ms |
3dabc.cssblocking | 26 ms | 476 B | 26 ms |
52458.cssblocking | 21 ms | 64.4 KB | 21 ms |
| 7 more requests | all done by 323 ms | 125.9 KB | |
LCP resource | 6 ms | 155.7 KB | 6 ms |
71 ms | 37.1 KB | 71 ms | |
82 ms | 47.2 KB | 82 ms | |
52 ms | 37.5 KB | 52 ms | |
0702 ms1.053 sFCP 396 msLCP 1.404 s |
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.
avoidScalingImagesThe page has 25 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.
googleTagManagerThe page is using Google Tag Manager, this is a performance risk since non-tech users can add JavaScript to your page.
Google Tag Manager makes it possible for non tech users to add scripts to your page that will downgrade performance.
longTasksThe page has 5 CPU long tasks with the total of 390 ms. The total blocking time is 126 ms and 1 long task before first contentful paint with total time of 64 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.
modernImageFormatsThe page ships 38 images (out of 38) 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
cacheHeadersThe page has 16 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 868.8 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.
cssSizeThe total CSS transfer size is 243.9 kB and uncompressed size is 1.7 MB. That is big and the CSS could most probably be smaller.
Delivering a massive amount of CSS to the browser is not the best thing you can do, because it means more work for the browser when parsing the CSS against the HTML and that makes the rendering slower. Try to send only the CSS that is used on that page. And make sure to remove CSS rules when they aren't used anymore.
| URL | Transfer | Content |
|---|---|---|
| https://www.siarv.it/siar/wp-content/cache/minify/52458.css | 64.0 KB | 378.4 KB |
| https://www.siarv.it/siar/wp-content/cache/minify/b1a86.css | 7.2 KB | 31.9 KB |
| https://www.siarv.it/siar/wp-content/cache/minify/3bcfd.css | 163.2 KB | 1.2 MB |
| https://www.siarv.it/siar/wp-content/cache/minify/3dabc.css | 90 B | 75 B |
| https://fonts.googleapis.com/css?family=Montserrat:700 | 1.0 KB | 1.8 KB |
| https://fonts.googleapis.com/css...oogleapis.com/css | 2.7 KB | 65.4 KB |
javascriptSizeThe total JavaScript transfer size is 671.2 kB and the uncompressed size is 2.3 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?
lazyLoadingImagesThe page has 8 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
avoidRenderBlockingThe page has 9 blocking requests and 0 in body parser blocking (5 JavaScript and 4 CSS).
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.
faviconThe favicon has no cache time.
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.
fewFontsThe page has 5 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.
imageSizeThe 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.
privateAssetsThe page has 4 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.
cacheHeadersLongThe page has 33 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.
decodingAsyncThe page has 12 images (out of 38) 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
optimalCssSizehttps://www.siarv.it/siar/wp-content/cache/minify/52458.css size is 65.5 kB (65509) and that is bigger than the limit of 25 kB. https://www.siarv.it/siar/wp-content/cache/minify/3bcfd.css size is 167.1 kB (167110) 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.
| URL | Transfer | Content |
|---|---|---|
| https://www.siarv.it/siar/wp-content/cache/minify/52458.css | 64.0 KB | 378.4 KB |
| https://www.siarv.it/siar/wp-content/cache/minify/3bcfd.css | 163.2 KB | 1.2 MB |
inlineCssThe page has both inline styles as well as it is requesting 5 CSS files inside of the head. Let's only inline CSS for really fast render.
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.
spofThe 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.
metaDescriptionThe page is missing a meta description.
Use a page description to make the page more relevant to search engines.
unnecessaryHeadersThere are 40 responses that sets both a max-age and expires header. There are 2 responses that sets a pragma no-cache header (that is a request header). There are 26 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.
thirdPartyThe page do 19% requests to third party domains (11 requests and 384.6 kB). First party is 47 requests and 1.9 MB. The regex .*siarv.* was used to calculate first/third party requests.
Do not load most of your content from third party URLs.
gaThe page is using Google Analytics meaning you share your users private information with Google. You should use analytics that care about user privacy, something like https://matomo.org.
Google Analytics share private user information with Google that your user hasn't agreed on sharing.
referrerPolicyNo <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
surveillanceThe page embeds 2 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.
contentSecurityPolicyHeaderSet a Content-Security-Policy header to mitigate cross-site scripting attacks. You can start with a Content-Security-Policy-Report-Only header, which only reports violations rather than blocking them.
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
crossOriginEmbedderPolicyHeaderSet 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
crossOriginOpenerPolicyHeaderSet 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
crossOriginResourcePolicyHeaderSet 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
nelHeaderSet 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
referrerPolicyHeaderSet 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/.
reportingEndpointsHeaderSet 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
strictTransportSecurityHeaderSet 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.
thirdPartyPrivacyThe page has 19% requests that are 3rd party (11 requests with a size of 384.6 kB). 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 11 survelliance requests and uses 3 survelliance tools. The page do 11 surveillance requests and uses 3 surveillance tools. The page do 3 analytics requests and uses 1 analytics tool. The page do 1 tag-manager request and uses 1 tag-manager 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.
xContentTypeOptionsHeaderSet X-Content-Type-Options: nosniff on the document response to prevent MIME-sniffing.
X-Content-Type-Options: nosniff prevents browsers from interpreting files as a different MIME type than what is declared in the Content-Type header. This blocks a class of cross-site scripting and content-type confusion attacks and should be set on every response. https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Content-Type-Options
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.
Document
What the page says it is and how large it rendered.
DOM structure
How much markup the browser has to build, style and lay out.
What the page stored on the client, and the network it was tested on.
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.
Data collected using Third Party Web version 0.29.2.
Data from run 1
0.0s0.5s0.9s1.2s1.7s2.0s2.4s2.7sWhen the page main content is rendered, collected via the Largest Contentful Paint API. Read more about Largest Contentful Paint.
body > div:eq(1) > div:eq(1) > div#banner-wrapper > div#rev_slider_2_1_forcefullwidth > div#rev_slider_2_1_wrapper > div#rev_slider_2_1 > ul > li:eq(0) > div:eq(0) > div
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:
How much the page's content shifts as it loads, collected via the Cumulative Layout Shift API.
One shift is 80% of your 0.008 CLS. div:eq(1) moved at 518 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.
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.
There are no custom configured scripts.
There are no custom extra metrics from scripting.
How the page is built.
https://www.siarv.it/eventi-passati/
| Header | Value |
|---|---|
connection | keep-alive |
content-encoding | gzip |
content-length | 23573 |
content-type | text/html; charset=UTF-8 |
date | Tue, 20 Oct 2026 16:24:06 GMT |
link | <https://www.siarv.it/wp-json/>; rel="https://api.w.org/", <https://www.siarv.it/wp-json/wp/v2/pages/5352>; rel="alternate"; title="JSON"; type="application/json", <https://www.siarv.it/?p=5352>; rel=shortlink |
permissions-policy | private-state-token-redemption=(self "https://www.google.com" "https://www.gstatic.com" "https://recaptcha.net" "https://challenges.cloudflare.com" "https://hcaptcha.com"), private-state-token-issuance=(self "https://www.google.com" "https://www.gstatic.com" "https://recaptcha.net" "https://challenges.cloudflare.com" "https://hcaptcha.com") |
upgrade | h2,h2c |
vary | Accept-Encoding |
x-cache-status | HIT |
x-served-by | www.siarv.it |
x-w3tc-cdn | ftp |
Transfer size2.2 MB
Content size5.2 MB
Requests58
| Content | Header Size | Transfer Size | Content Size | Requests |
|---|---|---|---|---|
| html | 1.4 KB | 23.0 KB | 99.8 KB | 2 |
| css | 1.5 KB | 238.2 KB | 1.6 MB | 6 |
| javascript | 6.0 KB | 655.5 KB | 2.2 MB | 17 |
| image | 9.0 KB | 1.1 MB | 1.1 MB | 25 |
| font | 0 b | 187.4 KB | 187.3 KB | 5 |
| favicon | 284 B | 1.1 KB | 1.1 KB | 1 |
| plain | 0 b | 463 B | 15 B | 2 |
| Total | 18.2 KB | 2.2 MB | 5.2 MB | 58 |
| Domain | Total download time | Transfer Size | Content Size | Requests |
|---|---|---|---|---|
| www.siarv.it | 3.262 s | 988.5 KB | 3.6 MB | 32 |
| cdn.siarv.it | 356 ms | 848.4 KB | 848.4 KB | 15 |
| fonts.googleapis.com | 206 ms | 3.7 KB | 67.2 KB | 2 |
| www.google-analytics.com | 170 ms | 21.4 KB | 51.1 KB | 2 |
| fonts.gstatic.com | 392 ms | 187.4 KB | 187.3 KB | 5 |
| www.googletagmanager.com | 269 ms | 163.1 KB | 469.5 KB | 1 |
| region1.google-analytics.com | 106 ms | N/A | 0 b | 1 |
| type | min | median | max |
|---|---|---|---|
| Expires | 0 seconds | 4 weeks | 1 year |
| Last modified | 0 seconds | 1 year | 28 years |
Includes requests done after load event end.
| Content | Transfer Size | Requests |
|---|---|---|
| html | 0 b | 0 |
| css | 0 b | 0 |
| javascript | 168.4 KB | 2 |
| image | 0 b | 0 |
| font | 0 b | 0 |
| favicon | 1.1 KB | 1 |
| plain | 0 b | 1 |
| Total | 169.5 KB | 4 |
Includes requests done after DOM content loaded.
| Content | Transfer Size | Requests |
|---|---|---|
| html | 22 B | 1 |
| css | 0 b | 0 |
| javascript | 189.2 KB | 4 |
| image | 162.4 KB | 7 |
| font | 0 b | 0 |
| favicon | 1.1 KB | 1 |
| plain | 463 B | 2 |
| Total | 353.2 KB | 15 |
--enableProfileRun to see where main-thread time went, blocking time and CPU cost per script, module and function, forced reflows and frame stability. The data is collected in one extra run, so the timing metrics of your measured runs stay untouched.Tasks ≥ 50 ms blocking the main thread, collected via the Long Task API.
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.
| Script | Frames | Time running | Blocking (share by run time) | Forced style & layout | Triggered by |
|---|---|---|---|---|---|
| 4476d.js | 4 | 219.2 ms | 71 ms | 72 ms | timer or animation callback, script tag |
| js3rd party | 1 | 113.2 ms | 64.4 ms | – | script tag |
| ca29e.js | 4 | 159.4 ms | 5 ms | 47.7 ms | script tag, timer or animation callback |
| 39133.js | 1 | 42.1 ms | 4.3 ms | 28.1 ms | script tag |
| d9704.js | 1 | 6.8 ms | 2.1 ms | – | script tag |
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.
1 more long frame carried no blocking time (nothing ran past the 50 ms threshold) — long, but harmless to INP and TBT.
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.
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.
Third party requests categorised by Third party web version 0.29.2.
Requests by category22
Transfer size2.2 MB
Content size5.2 MB
Requests58
Calculated using .*siarv.* (use --firstParty to configure).
| Content | Header Size | Transfer Size | Content Size | Requests |
|---|---|---|---|---|
| html | 1.4 KB | 23.0 KB | 99.8 KB | 2 |
| css | 1.5 KB | 234.5 KB | 1.6 MB | 4 |
| javascript | 6.0 KB | 471.5 KB | 1.7 MB | 15 |
| image | 9.0 KB | 1.1 MB | 1.1 MB | 25 |
| font | 0 b | 0 b | 0 b | 0 |
| favicon | 284 B | 1.1 KB | 1.1 KB | 1 |
| Total | 18.2 KB | 1.8 MB | 4.5 MB | 47 |
| Content | Header Size | Transfer Size | Content Size | Requests |
|---|---|---|---|---|
| html | 0 b | 0 b | 0 b | 0 |
| css | 0 b | 3.7 KB | 67.2 KB | 2 |
| javascript | 0 b | 184.0 KB | 520.6 KB | 2 |
| image | 0 b | 0 b | 0 b | 0 |
| font | 0 b | 187.4 KB | 187.3 KB | 5 |
| favicon | 0 b | 0 b | 0 b | 0 |
| plain | 0 b | 463 B | 15 B | 2 |
| Total | N/A | 375.6 KB | 775.1 KB | 11 |