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https://www.data.gouv.fr

Performance

· 16 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
77
GRADE
C
FIX
3
REVIEW
2
PASS
9
INFO
2

Performance-focused optimization plan with CWV assessment, top offenders, and time estimates

Mobile Desktop
31
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
93
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
100
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
100
SEO Measures basic SEO optimizations: meta tags, crawlability, link text, and mobile friendliness.

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

7.35 s

Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.

13.05 s

Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.

938 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.142

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

7.35 s

Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.

13.42 s

Page Load Progression

375 ms
750 ms
1.1 s
1.5 s
1.9 s
2.2 s
2.6 s
3.0 s
Checks
16
9 PASS 2 REVIEW 3 FIX
F
Page Weight Budget
Action
3.1 MB transferred, 143 requests
FIX
3.1 MB transferred, 143 requests
Warning::
Page weighs 8.6 MB (3.1 MB transferred)
Warning::
Images are 1.4 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 1.4 MB
Warning::
JavaScript is 1.0 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.0 MB
Info::
Fonts are 374 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 374 KB
Warning::
143 HTTP requests — consider bundling or reducing
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
Info::
Estimated 0.65 g CO2 per page load
3.1 MB / 2.4 MB budget
3.1 MB transferred
143 requests
0.65 g CO2 per page load
Images 1.4 MiB 46%
JavaScript 1.0 MiB 33%
Fonts 374.5 KiB 12%
CSS 188.2 KiB 6%
HTML 58.5 KiB 2%
Other 45.0 KiB 1%
Other 276 B 0%
Other 188 B 0%
0 2.4 MB 4.9 MB
Over budget

Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.

Why this matters

Image bandwidth is high — modern formats (WebP/AVIF) and resizing typically cut it 50%+.

Source: web.dev

Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.

Why this matters

JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.

Source: web.dev

Subset fonts to include only used characters, or switch to system font stacks.

Why this matters

Font payload is large — subset to used glyphs only, or fall back to system fonts (zero load time).

Source: web.dev font loading

Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.

Why this matters

High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.

Source: web.dev

F
JS Execution Cost
Action
3733ms total JS execution
FIX
3733ms total JS execution
Warning::
Unattributable: 1752ms CPU time
Warning::
https://www.data.gouv.fr/_nuxt/DeWFfL1o.js: 641ms CPU time
Warning::
https://www.data.gouv.fr/: 559ms CPU time
Warning::
https://stats.data.gouv.fr/matomo.js: 514ms CPU time
Warning::
https://www.data.gouv.fr/_nuxt/entry.BmkqFH0c.css: 266ms CPU time
Warning::
Third-party scripts: 2266ms (61% of total)

Main Thread Breakdown

Script Evaluation 48% Other 31% Style & Layout 12% Parse HTML & CSS 6%
ScriptTotalScriptingParse/CompileParty
Unattributable1752ms801ms0ms3rd
https://www.data.gouv.fr/_nuxt/DeWFfL1o.js641ms567ms9ms1st
https://www.data.gouv.fr/559ms5ms2ms1st
https://stats.data.gouv.fr/matomo.js514ms489ms17ms3rd
https://www.data.gouv.fr/_nuxt/entry.BmkqFH0c.css266ms0ms0ms1st
F
JS Bundles
Action
101 scripts, 642 KB unused
FIX
101 scripts, 642 KB unused
Warning::
https://www.data.gouv.fr/_nuxt/DeWFfL1o.js: 392 KB unused (70%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.data.gouv.fr/_nuxt/CLIvgYrS.js: 97 KB unused (72%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.data.gouv.fr/_nuxt/BIpomotR.js: 84 KB unused (89%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://stats.data.gouv.fr/matomo.js: 25 KB unused (51%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.data.gouv.fr/_nuxt/CiafoMRz.js: 21 KB unused (57%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 642 KB
642 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.data.gouv.fr/_nuxt/DeWFfL1o.js563 KB392 KB (70%)✓1st
https://www.data.gouv.fr/_nuxt/CLIvgYrS.js137 KB97 KB (72%)✓1st
https://www.data.gouv.fr/_nuxt/BIpomotR.js95 KB84 KB (89%)✓1st
https://stats.data.gouv.fr/matomo.js50 KB25 KB (51%)✓3rd
https://www.data.gouv.fr/_nuxt/CiafoMRz.js13 KB21 KB (57%)✓1st
https://www.data.gouv.fr/_nuxt/CiafoMRz.js0 KB21 KB (57%)✓1st
https://www.data.gouv.fr/_nuxt/Dn6wUxSO.js1 KB—✓1st
https://www.data.gouv.fr/_nuxt/BuZ0Vue4.js1 KB—✓1st
https://www.data.gouv.fr/_nuxt/BtxLH1pz.js21 KB—✓1st
https://www.data.gouv.fr/_nuxt/DExm8gmT.js1 KB—✓1st

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

C
Image Optimization
Action
20 images, 0 KB saveable
REVIEW
20 images, 0 KB saveable
Warning::
https://www.data.gouv.fr/_ipx/_/illustrations/data... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://static.data.gouv.fr/images/7c/ed09e56c864b... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.data.gouv.fr/_ipx/_/nuxt_images/logo_t... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.data.gouv.fr/_ipx/_/illustrations/disc... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
20 images 1.4 MB
0 oversized -0 KB
17 legacy format
4 missing dimensions CLS risk

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

B
HTTP Caching
public
REVIEW
public
Info::
Cache-Control header is set
Got: public
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

public

DirectiveValueMeaning
public—Any cache may store this response
A+
Third-Party Impact
3% third-party, 0 ms blocking
PASS
3% third-party, 0 ms blocking
Info::
Third-party code accounts for 3% of page weight (88.5 KiB of 3.1 MiB)
Info::
Third-party blocking time is low (0 ms)
97%
First-party Third-party
A+
Text Compression
All text resources are compressed
PASS
All text resources are compressed
Info::
All text resources are compressed
All text resources are properly compressed.
A+
Font Loading
7 fonts (374 KB)
PASS
7 fonts (374 KB)
Info::
7 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

7

374 KB total

Render-blocking

0

of 7

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s FCP 7.3 s LCP 13.1 shttps://www.data.gouv.fr/fonts/Marianne-700.woff2Marianne-700.woff2 https://www.data.gouv.fr/fonts/Marianne-700.woff2 — 41.4 KiB — 0 ms — font-display: swaphttps://www.data.gouv.fr/fonts/Marianne-400.woff2Marianne-400.woff2 https://www.data.gouv.fr/fonts/Marianne-400.woff2 — 40.6 KiB — 0 ms — font-display: swaphttps://www.data.gouv.fr/fonts/Marianne-800.woff2Marianne-800.woff2 https://www.data.gouv.fr/fonts/Marianne-800.woff2 — 41.4 KiB — 0 ms — font-display: swaphttps://www.data.gouv.fr/fonts/Spectral-400-Italic.woff2Spectral-400-Italic.woff2 https://www.data.gouv.fr/fonts/Spectral-400-Italic.woff2 — 79.9 KiB — 0 ms — font-display: swaphttps://www.data.gouv.fr/fonts/Marianne-500.woff2Marianne-500.woff2 https://www.data.gouv.fr/fonts/Marianne-500.woff2 — 41.2 KiB — 0 ms — font-display: swaphttps://www.data.gouv.fr/fonts/Marianne-300.woff2Marianne-300.woff2 https://www.data.gouv.fr/fonts/Marianne-300.woff2 — 40.7 KiB — 0 ms — font-display: swaphttps://www.data.gouv.fr/fonts/Spectral-700-Italic.woff2Spectral-700-Italic.woff2 https://www.data.gouv.fr/fonts/Spectral-700-Italic.woff2 — 89.2 KiB — 0 ms — font-display: swap
Marianne-700.woff2 woff2 swap
Size 41 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Marianne-400.woff2 woff2 swap
Size 41 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Marianne-800.woff2 woff2 swap
Size 41 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Spectral-400-Italic.woff2 woff2 swap
Size 80 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Marianne-500.woff2 woff2 swap
Size 41 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Marianne-300.woff2 woff2 swap
Size 41 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Spectral-700-Italic.woff2 woff2 swap
Size 89 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Optimization checklist
  • Preload critical fonts (priority=high)
  • Use woff2 format for all fonts
  • Set font-display to swap, optional, or fallback
  • Subset large fonts (≤100 KB each)
A+
Resource Caching
All resources properly cached
PASS
All resources properly cached
Info::
No caching issues found
All static resources have appropriate caching headers.
A+
Critical Rendering Path
No render-blocking resources
PASS
No render-blocking resources
Info::
No render-blocking resources detected
A+
Resource Hints
13 hints, 0 missing preconnects
PASS
13 hints, 0 missing preconnects
Info::
Page uses 13 resource hint(s)

Current Resource Hints

preconnect
—
preload
1
dns-prefetch
—
prefetch
+2
12

13 resource hints configured

A+
Render-Blocking Resources
No render-blocking resources detected
PASS
No render-blocking resources detected
Info::
No render-blocking resources detected in <head>
A+
Third-Party Resources
No third-party resources detected
PASS
No third-party resources detected
A+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: OVHcloud

Network Waterfall
143 requests over 0ms
INFO

Performance analysis not available for this result.

Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
61% of JavaScript execution is third-party
First-party Third-party 2266ms · 50KB · €25/mo
Unattributable
Other
Costly
Execution 1752ms
Transfer 0 KB
Monthly Cost €19/mo
stats.data.gouv.fr
Other
Costly
Execution 514ms
Transfer 50 KB
Unused 51%
Monthly Cost €6/mo

These scripts may cost more than they're worth

  • Unattributable adds 1752ms and costs ~€19/month
  • stats.data.gouv.fr adds 514ms and costs ~€6/month

61% of JavaScript execution time comes from third-party scripts.

Why this matters

Third-party scripts (analytics, ads, social, A/B testing) often dominate execution time — every one is a perf-and-privacy tax.

Learn more ▾

Each third-party script is a black box: you don't control when it loads, what it executes, or how much it grows. They often account for a major share of total blocking time on average sites (HTTP Archive's Web Almanac documents the trend). Audit which ones you actually need, defer the rest, and use facade patterns (lite-youtube, lite-vimeo) for embedded media.

Source: web.dev / HTTP Archive Web Almanac

Unattributable takes 1752ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

stats.data.gouv.fr takes 514ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

51% of stats.data.gouv.fr's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

How third-party costs are calculated

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

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