57of 100
51of 100
lcb.cnrs.fr
DLevel 2 · Slow
FLevel 2 · Slow
WordPress⚡ xSpeed v1.4.2MCP signal present
160msTTFB
63Lighthouse desktop · graded
55Lighthouse mobile
8.3sLCP
0.00CLS
gzipCompression
HITCache
Lab data: Lighthouse 13.5.0 desktop run, graded above · Reproduce this run on PageSpeed Insights ↗ · Mobile: 51 (F) —
Real visitors · Chrome UX Report · desktop · whole site (this page has too little traffic of its own) ·
passes Core Web Vitals
2.5sLCP (p75)
0.00CLS (p75)
Why is this different from the score in my browser?
The graded score is the desktop run. Lighthouse 13.5.0 runs at Google through the PageSpeed Insights API on a desktop profile with no CPU or network throttling — close to what Chrome DevTools on a laptop, GTmetrix's default test and the PageSpeed API (which defaults to desktop) all measure, so this is the number you should be able to reproduce: run it yourself on PageSpeed Insights.
Google ranks on mobile. That run happens too, on an emulated mid-range Android with a 4× CPU slowdown and a throttled connection, and the same page routinely scores 30–50 points lower there. Neither number is wrong — they are different tests. On this page the mobile run scored 51 (F) against 57 (D) here — to see every check graded on that run.
Lighthouse also varies a few points run to run on the same URL. Treat a trend across several scans as the signal, never a single digit.
Lab data: Google PageSpeed Insights (Lighthouse, desktop). Server probes (TTFB, compression, cache, headers) are measured separately from Vilnius, Lithuania (EU).
160msTTFB
63Lighthouse desktop
55Lighthouse mobile · graded
36.3sLCP
0.00CLS
gzipCompression
HITCache
Lab data: Lighthouse 13.5.0 mobile run, graded above · Reproduce this run on PageSpeed Insights ↗ · Desktop: 57 (D) —
Real visitors · Chrome UX Report · mobile · whole site (this page has too little traffic of its own) ·
fails Core Web Vitals
3.1sLCP (p75)
0.00CLS (p75)
Why is this different from the score in my browser?
This view grades the mobile run. Lighthouse 13.5.0 runs at Google through the PageSpeed Insights API on an emulated mid-range Android with a 4× CPU slowdown and a throttled connection. Chrome DevTools on your own machine, on the Desktop preset, applies almost none of that, and the same page routinely scores 30–50 points higher there. Neither number is wrong — they are different tests.
Mobile is what Google ranks on, so this is the number that affects your
search performance. On this page the desktop run scored 57 (D) against
51 (F) here —
to see every check graded on that run. To reproduce it, open the same run on PageSpeed Insights,
or pass strategy=mobile to the PageSpeed API — it defaults to desktop.
Lighthouse also varies a few points run to run on the same URL. Treat a trend across several scans as the signal, never a single digit.
Lab data: Google PageSpeed Insights (Lighthouse, mobile). Server probes (TTFB, compression, cache, headers) are measured separately from Vilnius, Lithuania (EU).
Lab performance (Lighthouse)D63
3/5 checks passed · 25.3/40 pts Jump to section ↓
Server response & cachingB81
4/5 checks passed · 22/27 pts Jump to section ↓
Asset optimizationF0
0/5 checks passed · 0/20 pts Jump to section ↓
Platform & xSpeed readinessB80
2/3 checks passed · 8/10 pts Jump to section ↓
Lab performance (Lighthouse)F50
2/5 checks passed · 19.9/40 pts Jump to section ↓
Server response & cachingB81
4/5 checks passed · 22/27 pts Jump to section ↓
Asset optimizationF0
0/5 checks passed · 0/20 pts Jump to section ↓
Platform & xSpeed readinessB80
2/3 checks passed · 8/10 pts Jump to section ↓
Top fixes ranked by points recovered · desktop
Top fixes ranked by points recovered · mobile
MCP status reported — verify client access
- ✓WordPressDetected
- ✓xSpeed Cache installedv1.4.2
- ✓MCP signal presentThe report indicates MCP availability. This does not verify client authentication or control.
- →xSpeed Hub signalOptional: review Hub configuration and confirm authorized site membership at app.xspeedcache.com.
10 of these checks map to an xSpeed feature. lcb.cnrs.fr's report indicates that xSpeed MCP is available. This scan did not verify client credentials; if your client is configured and authenticated, use this prompt:
If you are authenticated to my site's xSpeed MCP server, read the failing checks from https://xspeedcache.com/scan/r/lcb-cnrs-fr-35b3fbe1e9.md, apply the fixes: enable page caching, compression, minification and lazy loading, warm the cache, then run a benchmark and re-scan at https://xspeedcache.com/scan to confirm the score improved.Hosting is the other half.
xSpeed makes any host faster, but a cache is only as fast as the server behind a MISS.
xCloud — managed hosting from the team behind xSpeed — gives the cache an origin tuned for it, with agent/MCP access built in and bring-your-own-server pricing.
Explore xCloud.host →
Run this scan without the form
Plug xSpeed Scan into your agent stack, or test any site from a chat.
Connect this scanner to your AI assistant
Free. No API key, no sign-up. Scan any public site and get the same graded report as this one, with the fix for every failing check.
Endpoint
https://xspeedcache.com/scan/mcpClaude Code — one command
claude mcp add --transport http xspeed-scan https://xspeedcache.com/scan/mcpClaude Desktop, Cursor, or any MCP client — add to your config
{
"mcpServers": {
"xspeed-scan": {
"type": "http",
"url": "https://xspeedcache.com/scan/mcp"
}
}
}run_speed_scanScan any public URL and return this whole graded report.get_speed_scanRead a scan already run, by its id.
D
63/100
Lab performance (Lighthouse)
3/5 checks passed · 25.3/40 pts earned
Partial
Lighthouse performance score (desktop) 11.3/18 pts
63/100 (Lighthouse 13.5.0, desktop)
The composite Lighthouse score — every fix below moves it.
xSpeed Free
AI Optimize
AI prompt
Using my site's xSpeed MCP connection: run optimize_site, then run_benchmark to verify the score improved.Guidelines: Lighthouse performance scoring
Fail
Largest Contentful Paint ≤ 2.5s 0/8 pts
LCP 8.3s
Serve the hero content faster: cache the page, preload the LCP image, and ship critical CSS.
xSpeed Free
Page Cache + Preloader (Critical CSS in Pro)
AI prompt
Using my site's xSpeed MCP connection: enable page caching, start the preloader, and (on Pro) generate critical CSS for this page; then re-test LCP.Guidelines: web.dev — Largest Contentful Paint · Optimize LCP
Pass
Pass
Pass
B
81/100
Server response & caching
4/6 checks passed · 22/27 pts earned
Pass
Time to first byte ≤ 200ms 8/8 pts
TTFB 160ms measured from Vilnius, Lithuania (EU) (best of 2 requests). This includes the network round trips between us and your origin, not just server time. Google measured your server responding in 32ms from its own network — the gap between the two numbers is distance, not your server.
Guidelines: web.dev — Time to First Byte
Pass
Page served from cache 7/7 pts
WP Fastest Cache served its stored file: the "file was created" comment is there without the "need to refresh" line it adds while building.
Guidelines: MDN — HTTP caching
Pass
HTML compression (bytes on the wire) 5/5 pts
Content-Encoding: gzip — 49KB on the wire
Guidelines: MDN — Content-Encoding · RFC 7932 — Brotli
Fail
Efficient cache policy on static assets 0/5 pts
Fails the Lighthouse cache-policy audit — 8 files: Capture-decran-2023-03-16-a-15.34.07.png, IMG_9187-scaled.jpg, Labo.png…
Give CSS/JS/images long Cache-Control lifetimes so repeat views are free.
xSpeed Free
Browser Cache
AI prompt
Using my site's xSpeed MCP connection: enable browser-cache headers for static assets, then re-run the audit.Guidelines: Lighthouse — Efficient cache policy
Info
CDN edge serves the page —
No CDN signature detected
Optional: put a CDN or Cloudflare in front for global edge delivery.
xSpeed Free
Cloudflare integration / CDN rewriter
AI prompt
Using my site's xSpeed MCP connection: connect Cloudflare (or configure the CDN rewriter) and purge, then re-scan.Guidelines: web.dev — Content delivery networks
Pass
Clean redirect chain 2/2 pts
No redirects — the URL answers directly
Guidelines: Lighthouse — Avoid redirects
F
0/100
Asset optimization
0/5 checks passed · 0/20 pts earned
Fail
No render-blocking resources 0/5 pts
Fails the Lighthouse audit — 8 files: css/post-4.css, 1qda0hkw/fdc5r.css, 6oj4mp0o/fdc5r.css… · ~1.1s of first paint
CSS/JS in <head> blocks first paint. Inline the critical CSS and defer the rest.
xSpeed Pro
Critical CSS + Unused CSS removal
AI prompt
Using my site's xSpeed MCP connection: generate critical CSS for the top pages and enable unused-CSS removal, then re-test.Guidelines: Lighthouse — Render-blocking resources
Fail
Minified CSS and JavaScript 0/4 pts
Fails the Lighthouse audit — 4 files: fdc5r.css, fdc5r.js, tarteaucitron.services.js…
Ship minified assets — whitespace and comments are pure transfer waste.
xSpeed Free
HTML/CSS/JS Minify
AI prompt
Using my site's xSpeed MCP connection: enable HTML, CSS and JS minification, purge the cache, and re-test.Guidelines: Lighthouse — Minify CSS · Minify JavaScript
Fail
Modern, optimized image formats 0/4 pts
Fails the Lighthouse audit — 8 files: Capture-decran-2023-03-16-a-15.34.07.png, Labo.png, Capture-decran-2026-10-12-a-15.03.44.png… · ~2.9s of first paint
Serve WebP/AVIF at the right compression — usually the single largest byte saving.
xSpeed Pro
Image Converter (WebP/AVIF)
AI prompt
Using my site's xSpeed MCP connection: enable WebP/AVIF conversion with URL rewriting, then re-test image audits.Guidelines: Lighthouse — Modern image formats
Fail
LCP image discoverable early 0/4 pts
Fails the Lighthouse audit
The largest image must be in the HTML and preloaded — never lazy-loaded or script-injected.
xSpeed Free
Resource Hints (preload) + Lazy Load exclusions
AI prompt
Using my site's xSpeed MCP connection: preload the LCP image for this page and exclude it from lazy loading, then re-test LCP.Guidelines: web.dev — Optimize LCP · Lighthouse — LCP request discovery
Fail
Total page weight (≤ 350KB for full marks) 0/3 pts
13.4MB transferred — over 1,500KB
Page weight is what decides mobile LCP once the server is fast. Resize images to the size they display at, lazy-load below the fold, and drop scripts the page does not use.
xSpeed Free
Minify + Lazy Load + Image Converter (Pro)
AI prompt
Using my site's xSpeed MCP connection: enable minification and lazy loading (and image conversion on Pro), then re-check page weight.Guidelines: Lighthouse — Total byte weight
B
80/100
Platform & xSpeed readiness
2/4 checks passed · 8/10 pts earned
Info
Platform
WordPress detected (Elementor 4.3.4; features: additional_custom_breakpoints; settings: css_print_method-internal, google_font-enabled, font_display-auto)
Informational.
Pass
Caching plugin active 4/4 pts
WP Fastest Cache (WP Fastest Cache HTML signature)
Guidelines: WordPress.org — Optimization: caching
Partial
Powered by xSpeed 2/4 pts
Running WP Fastest Cache instead
xSpeed bundles caching, minification, lazy-load, image optimization and a built-in MCP endpoint that requires an authenticated client for management actions; it also imports settings from other caching plugins in one click.
xSpeed Free
xSpeed Migration (one-click import)
AI prompt
Install xSpeed and use its Migration tool to import your current caching settings, then deactivate the old plugin.Guidelines: xSpeed — feature overview · xSpeed vs other cache plugins
Pass
xSpeed MCP route responded 2/2 pts
The public xSpeed MCP route returned its expected unauthenticated challenge. This confirms route responsiveness only; client authentication and control were not tested.
Guidelines: Model Context Protocol · xSpeed documentation
F
50/100
Lab performance (Lighthouse)
2/5 checks passed · 19.9/40 pts earned
Partial
Lighthouse performance score (mobile) 9.9/18 pts
55/100 (Lighthouse 13.5.0, mobile)
The composite Lighthouse score — every fix below moves it.
xSpeed Free
AI Optimize
AI prompt
Using my site's xSpeed MCP connection: run optimize_site, then run_benchmark to verify the score improved.Guidelines: Lighthouse performance scoring
Fail
Largest Contentful Paint ≤ 2.5s 0/8 pts
LCP 36.3s
Serve the hero content faster: cache the page, preload the LCP image, and ship critical CSS.
xSpeed Free
Page Cache + Preloader (Critical CSS in Pro)
AI prompt
Using my site's xSpeed MCP connection: enable page caching, start the preloader, and (on Pro) generate critical CSS for this page; then re-test LCP.Guidelines: web.dev — Largest Contentful Paint · Optimize LCP
Pass
Pass
Fail
First Contentful Paint ≤ 1.8s 0/4 pts
FCP 8.0s
First paint is gated on server response and render-blocking CSS.
xSpeed Free
Page Cache + CSS Minify
AI prompt
Using my site's xSpeed MCP connection: enable page caching and CSS minification, then re-test First Contentful Paint.Guidelines: web.dev — First Contentful Paint
B
81/100
Server response & caching
4/6 checks passed · 22/27 pts earned
Pass
Time to first byte ≤ 200ms 8/8 pts
TTFB 160ms measured from Vilnius, Lithuania (EU) (best of 2 requests). This includes the network round trips between us and your origin, not just server time. Google measured your server responding in 33ms from its own network — the gap between the two numbers is distance, not your server.
Guidelines: web.dev — Time to First Byte
Pass
Page served from cache 7/7 pts
WP Fastest Cache served its stored file: the "file was created" comment is there without the "need to refresh" line it adds while building.
Guidelines: MDN — HTTP caching
Pass
HTML compression (bytes on the wire) 5/5 pts
Content-Encoding: gzip — 49KB on the wire
Guidelines: MDN — Content-Encoding · RFC 7932 — Brotli
Fail
Efficient cache policy on static assets 0/5 pts
Fails the Lighthouse cache-policy audit — 8 files: Capture-decran-2023-03-16-a-15.34.07.png, IMG_9187-scaled.jpg, Labo.png…
Give CSS/JS/images long Cache-Control lifetimes so repeat views are free.
xSpeed Free
Browser Cache
AI prompt
Using my site's xSpeed MCP connection: enable browser-cache headers for static assets, then re-run the audit.Guidelines: Lighthouse — Efficient cache policy
Info
CDN edge serves the page —
No CDN signature detected
Optional: put a CDN or Cloudflare in front for global edge delivery.
xSpeed Free
Cloudflare integration / CDN rewriter
AI prompt
Using my site's xSpeed MCP connection: connect Cloudflare (or configure the CDN rewriter) and purge, then re-scan.Guidelines: web.dev — Content delivery networks
Pass
Clean redirect chain 2/2 pts
No redirects — the URL answers directly
Guidelines: Lighthouse — Avoid redirects
F
0/100
Asset optimization
0/5 checks passed · 0/20 pts earned
Fail
No render-blocking resources 0/5 pts
Fails the Lighthouse audit — 8 files: linkblock.js, footer.js, ecs-color-scheme.min.css… · ~6.8s of first paint
CSS/JS in <head> blocks first paint. Inline the critical CSS and defer the rest.
xSpeed Pro
Critical CSS + Unused CSS removal
AI prompt
Using my site's xSpeed MCP connection: generate critical CSS for the top pages and enable unused-CSS removal, then re-test.Guidelines: Lighthouse — Render-blocking resources
Fail
Minified CSS and JavaScript 0/4 pts
Fails the Lighthouse audit — 7 files: embedpress.css, tarteaucitron.css, tarteaucitron.services.js…
Ship minified assets — whitespace and comments are pure transfer waste.
xSpeed Free
HTML/CSS/JS Minify
AI prompt
Using my site's xSpeed MCP connection: enable HTML, CSS and JS minification, purge the cache, and re-test.Guidelines: Lighthouse — Minify CSS · Minify JavaScript
Fail
Modern, optimized image formats 0/4 pts
Fails the Lighthouse audit — 8 files: Capture-decran-2023-03-16-a-15.34.07.png, Labo.png, Capture-decran-2026-10-12-a-15.03.44.png… · ~2.9s of first paint
Serve WebP/AVIF at the right compression — usually the single largest byte saving.
xSpeed Pro
Image Converter (WebP/AVIF)
AI prompt
Using my site's xSpeed MCP connection: enable WebP/AVIF conversion with URL rewriting, then re-test image audits.Guidelines: Lighthouse — Modern image formats
Fail
LCP image discoverable early 0/4 pts
Fails the Lighthouse audit
The largest image must be in the HTML and preloaded — never lazy-loaded or script-injected.
xSpeed Free
Resource Hints (preload) + Lazy Load exclusions
AI prompt
Using my site's xSpeed MCP connection: preload the LCP image for this page and exclude it from lazy loading, then re-test LCP.Guidelines: web.dev — Optimize LCP · Lighthouse — LCP request discovery
Fail
Total page weight (≤ 350KB for full marks) 0/3 pts
13.5MB transferred — over 1,500KB
Page weight is what decides mobile LCP once the server is fast. Resize images to the size they display at, lazy-load below the fold, and drop scripts the page does not use.
xSpeed Free
Minify + Lazy Load + Image Converter (Pro)
AI prompt
Using my site's xSpeed MCP connection: enable minification and lazy loading (and image conversion on Pro), then re-check page weight.Guidelines: Lighthouse — Total byte weight
B
80/100
Platform & xSpeed readiness
2/4 checks passed · 8/10 pts earned
Info
Platform
WordPress detected (Elementor 4.3.4; features: additional_custom_breakpoints; settings: css_print_method-internal, google_font-enabled, font_display-auto)
Informational.
Pass
Caching plugin active 4/4 pts
WP Fastest Cache (WP Fastest Cache HTML signature)
Guidelines: WordPress.org — Optimization: caching
Partial
Powered by xSpeed 2/4 pts
Running WP Fastest Cache instead
xSpeed bundles caching, minification, lazy-load, image optimization and a built-in MCP endpoint that requires an authenticated client for management actions; it also imports settings from other caching plugins in one click.
xSpeed Free
xSpeed Migration (one-click import)
AI prompt
Install xSpeed and use its Migration tool to import your current caching settings, then deactivate the old plugin.Guidelines: xSpeed — feature overview · xSpeed vs other cache plugins
Pass
xSpeed MCP route responded 2/2 pts
The public xSpeed MCP route returned its expected unauthenticated challenge. This confirms route responsiveness only; client authentication and control were not tested.
Guidelines: Model Context Protocol · xSpeed documentation
Past scans of lcb.cnrs.fr newest first · every report keeps its link
| Scanned | Score | Grade | Graded on | TTFB | Lighthouse | |
|---|---|---|---|---|---|---|
| 2026-10-14 15:23 UTC | 64 | D | desktop | 158ms | 61 | View report → |
| 2026-10-14 11:04 UTC | 64 | D | desktop | 158ms | 59 | View report → |
| 2026-10-14 10:31 UTC | 64 | D | desktop | 156ms | 59 | View report → |
| 2026-10-13 14:54 UTC this report | 57 | D | desktop | 160ms | 63 |
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