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https://www.data.gouv.fr

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
77
GRADE
C
FIX
2
REVIEW
3
PASS
7
INFO
2

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

Mobile Desktop
84
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
98
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
96
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.

1.36 s

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

1.98 s

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

129 ms

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

0.008

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

1.36 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.

2.01 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
14
7 PASS 3 REVIEW 2 FIX
D
Page Weight Budget
Action
2.6 MB transferred, 160 requests
FIX
2.6 MB transferred, 160 requests
Warning::
Page weighs 8.2 MB (2.6 MB transferred)
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 457 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 457 KB
Warning::
160 HTTP requests — consider bundling or reducing
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
Info::
Estimated 0.54 g CO2 per page load
2.6 MB / 2.4 MB budget
2.6 MB transferred
160 requests
0.54 g CO2 per page load
JavaScript 1.0 MiB 41%
Images 803.3 KiB 31%
Fonts 457.0 KiB 17%
CSS 188.3 KiB 7%
HTML 58.6 KiB 2%
Other 45.0 KiB 2%
Other 299 B 0%
Other 188 B 0%
0 2.4 MB 4.9 MB
Over budget

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 Bundles
Action
115 scripts, 640 KB unused
FIX
115 scripts, 640 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 (56%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 640 KB
640 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 (56%)✓1st
https://www.data.gouv.fr/_nuxt/CiafoMRz.js0 KB21 KB (56%)✓1st
https://www.data.gouv.fr/_nuxt/ChdArrcg.js1 KB—✓1st
https://www.data.gouv.fr/_nuxt/Bzod7VQI.js8 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/nuxt_images/homepage/data... 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.
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/_/illustrations/data... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.data.gouv.fr/nuxt_images/homepage/reus... 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.
20 images 803 KB
0 oversized -0 KB
17 legacy format
6 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

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
JS Execution Cost
913ms total JS execution
REVIEW
913ms total JS execution
Warning::
Unattributable: 429ms CPU time
Info::
https://www.data.gouv.fr/_nuxt/DeWFfL1o.js: 222ms CPU time
Info::
https://www.data.gouv.fr/: 143ms CPU time
Info::
https://stats.data.gouv.fr/matomo.js: 119ms CPU time
Warning::
Third-party scripts: 548ms (60% of total)

Main Thread Breakdown

Script Evaluation 57% Other 26% Style & Layout 11% Parse HTML & CSS 3%
ScriptTotalScriptingParse/CompileParty
Unattributable429ms243ms0ms3rd
https://www.data.gouv.fr/_nuxt/DeWFfL1o.js222ms204ms2ms1st
https://www.data.gouv.fr/143ms1ms1ms1st
https://stats.data.gouv.fr/matomo.js119ms114ms3ms3rd
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 2.6 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
9 fonts (457 KB)
PASS
9 fonts (457 KB)
Info::
9 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

9

457 KB total

Render-blocking

0

of 9

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s 1.5 s 2.0 s FCP 1.4 s LCP 2.0 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-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-400-Italic.woff2Marianne-400-Italic.woff2 https://www.data.gouv.fr/fonts/Marianne-400-Italic.woff2 — 43.5 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-300.woff2Marianne-300.woff2 https://www.data.gouv.fr/fonts/Marianne-300.woff2 — 40.6 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: swaphttps://www.data.gouv.fr/fonts/URWGothic-SemiBold.woff2URWGothic-SemiBold.woff2 https://www.data.gouv.fr/fonts/URWGothic-SemiBold.woff2 — 39.1 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-500.woff2 woff2 swap
Size 41 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Marianne-400-Italic.woff2 woff2 swap
Size 43 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-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
URWGothic-SemiBold.woff2 woff2 swap
Size 39 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
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
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
160 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
60% of JavaScript execution is third-party
First-party Third-party 548ms · 50KB · €6/mo
Unattributable
Other
Costly
Execution 429ms
Transfer 0 KB
Monthly Cost €5/mo
stats.data.gouv.fr
Other
Optional
Execution 119ms
Transfer 50 KB
Unused 51%
Monthly Cost €1/mo

These scripts may cost more than they're worth

  • Unattributable adds 429ms and costs ~€5/month

60% 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 429ms 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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