https://stf.xelta.ai/ai-studio/xelta-prism
Tested 2026-07-31 12:58:34 using Chrome 150.0.7871.186 (runtime settings)
Use --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 160 ms on a 26 ms first byte; the 1 render-blocking request was done by 56 ms and the remaining ~104 ms is style and layout work.
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 gap after the bars is style and layout work.
| Request | When it loaded | Transfer | Download |
|---|---|---|---|
document | 21 ms | 6.6 KB | 19 ms |
main.cssblocking | 8 ms | 2.8 KB | 8 ms |
040 ms80 msFCP · LCP 160 ms |
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.
cacheHeadersThe page has 6 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 10.5 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.
responseOkThe page has 2 error responses. The page has 1 response with code 404. The page has 1 response with code 502.
Your page should never request assets that return a 400 or 500 error. These requests are never cached. If that happens something is broken. Please fix it.
compressAssetsThe page has 1 request that are served uncompressed. You could save a lot of bytes by sending them compressed instead.
In the early days of the Internet there were browsers that didn't support compressing (gzipping) text content. They do now. Make sure you compress HTML, JSON, JavaScript, CSS and SVG. It will save bytes for the user; making the page load faster and use less bandwith.
| URL | Transfer | Content |
|---|---|---|
| https://stf.xelta.ai/ai-studio/xelta-prism | 6.6 KB | 6.2 KB |
privateAssetsThe page has 2 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.
inlineCssThe page uses HTTP/3 and loads 1 CSS request in head. Inline the critical CSS to avoid render-blocking on the first byte and lazy load the rest.
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.
cacheHeadersLongThe page has 1 request 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.
metaDescriptionThe page is missing a meta description.
Use a page description to make the page more relevant to search engines.
unnecessaryHeadersThere are 1 response that sets both a max-age and expires header. There are 8 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.
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
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
permissionsPolicyHeaderSet 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
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.
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.
0.0s0.2sWhen the page main content is rendered, collected via the Largest Contentful Paint API. Read more about Largest Contentful Paint.
body > div#cf-wrapper > div#cf-error-details > header > h1 > span:eq(0)
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.
How much the page's content shifts as it loads, collected via the Cumulative Layout Shift API.
No layout shifts were detected on this page.
Timing data the server chose to expose through Server-Timing response headers on the main document — typically backend time, cache status or experiment flags.
| Name | Duration | Description |
|---|---|---|
cfEdge | 5 ms | – |
cfOrigin | 2 ms | – |
cfExtPri | 0 ms | – |
There are no custom configured scripts.
There are no custom extra metrics from scripting.
How the page is built.
https://stf.xelta.ai/ai-studio/xelta-prism
| Header | Value |
|---|---|
alt-svc | h3=":443"; ma=86400 |
cache-control | private, max-age=0, no-store, no-cache, must-revalidate, post-check=0, pre-check=0 |
cf-ray | a23cc6819886b330-BOM |
content-length | 6387 |
content-type | text/html; charset=UTF-8 |
date | Fri, 31 Jul 2026 12:58:35 GMT |
expect-ct | max-age=86400, enforce |
expires | Thu, 01 Jan 1970 00:00:01 GMT |
priority | u=0,i |
referrer-policy | same-origin strict-origin-when-cross-origin |
retry-after | 60 |
server | cloudflare |
server-timing | cfEdge;dur=5,cfOrigin;dur=2 cfExtPri |
x-content-type-options | nosniff |
x-frame-options | SAMEORIGIN |
x-xss-protection | 1; mode=block |
| URL | Type | Transfer Size | Content Size |
|---|---|---|---|
| https://stf.xelta.ai/favicon.ico | html | 19.3 KB | 113.2 KB |
| https://stf.xelta.ai...tudio/xelta-prism | html | 6.6 KB | 6.2 KB |
| https://stf.xelta.ai...i/styles/main.css | css | 2.8 KB | 7.8 KB |
| https://stf.xelta.ai...cf-icon-cloud.png | image | 1.9 KB | 1.4 KB |
| https://stf.xelta.ai...f-icon-server.png | image | 1.8 KB | 1.4 KB |
| https://stf.xelta.ai...es/cf-icon-ok.png | image | 1.4 KB | 946 B |
| https://stf.xelta.ai...cf-icon-error.png | image | 1.3 KB | 854 B |
| https://stf.xelta.ai...-icon-browser.png | image | 980 B | 484 B |
Transfer size10.2 KB
Content size12.9 KB
Requests6
| Content | Header Size | Transfer Size | Content Size | Requests |
|---|---|---|---|---|
| css | 0 b | 2.8 KB | 7.8 KB | 1 |
| image | 0 b | 7.5 KB | 5.0 KB | 5 |
| Total | 0 b | 10.2 KB | 12.9 KB | 6 |
| Domain | Total download time | Transfer Size | Content Size | Requests |
|---|---|---|---|---|
| stf.xelta.ai | 153 ms | 36.2 KB | 132.3 KB | 8 |
| type | min | median | max |
|---|---|---|---|
| Expires | 0 seconds | 0 seconds | 4 weeks |
Includes requests done after load event end.
| Content | Transfer Size | Requests |
|---|---|---|
| html | 0 b | 0 |
| css | 0 b | 0 |
| javascript | 0 b | 0 |
| image | 0 b | 0 |
| font | 0 b | 0 |
| favicon | 0 b | 0 |
| Total | 19.3 KB | 1 |
Includes requests done after DOM content loaded.
| Content | Transfer Size | Requests |
|---|---|---|
| html | 0 b | 0 |
| css | 0 b | 0 |
| javascript | 0 b | 0 |
| image | 0 b | 0 |
| font | 0 b | 0 |
| favicon | 0 b | 0 |
| Total | 19.3 KB | 1 |
Third party requests categorised by Third party web version 0.29.2.
No third-party requests detected
Every request on this page resolved to a first-party domain. There are no entries in Third party web to attribute, no third-party tools to enumerate, and no third-party cookies set. If you expected to see entries here you can fine-tune the first-party domain list with --firstParty.
Calculated using .*xelta.* (use --firstParty to configure).
| Content | Header Size | Transfer Size | Content Size | Requests |
|---|---|---|---|---|
| html | 0 b | 0 b | 0 b | 0 |
| css | 0 b | 2.8 KB | 7.8 KB | 1 |
| javascript | 0 b | 0 b | 0 b | 0 |
| image | 0 b | 7.5 KB | 5.0 KB | 5 |
| font | 0 b | 0 b | 0 b | 0 |
| favicon | 0 b | 0 b | 0 b | 0 |
| Total | N/A | 36.2 KB | 132.3 KB | 8 |