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Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
77
GRADE
C
FIX
4
REVIEW
3
PASS
6
INFO
2

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

Mobile Desktop
92
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
100
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.

982 ms

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

1.50 s

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

30 ms

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

0.020

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

1.42 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.

1.50 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
15
6 PASS 3 REVIEW 4 FIX
D
Third-Party Impact
Action
100% third-party, 0 ms blocking
FIX
100% third-party, 0 ms blocking
Warning::
Third-party code accounts for 100% of page weight (1.6 MiB of 1.6 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
F
JS Bundles
Action
33 scripts, 523 KB unused
FIX
33 scripts, 523 KB unused
Warning::
https://www.groupe-sncf.com/_next/static/chunks/05...: 215 KB unused (84%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.groupe-sncf.com/_next/static/chunks/14...: 76 KB unused (79%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-PW6...: 67 KB unused (54%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://sdk.privacy-center.org/sdk/22ecd6bfac93de6...: 54 KB unused (53%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.groupe-sncf.com/_next/static/chunks/57...: 47 KB unused (82%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 523 KB
523 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.groupe-sncf.com/_next/static/chunks/05f6971a-3deaa127f637de56.js258 KB215 KB (84%)✓3rd
https://www.groupe-sncf.com/_next/static/chunks/1416-4620eb662f313595.js102 KB76 KB (79%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-PW6KXC5Z&gtm_auth=&gtm_preview=&gtm_cookies_win=x123 KB67 KB (54%)✓3rd
https://sdk.privacy-center.org/sdk/22ecd6bfac93de604efec0b75b2c796ee1675f92/modern/sdk.22ecd6bfac93de604efec0b75b2c796ee1675f92.js102 KB54 KB (53%)✓3rd
https://www.groupe-sncf.com/_next/static/chunks/5771-57f01415e13d0e00.js58 KB47 KB (82%)✓3rd
https://www.groupe-sncf.com/_next/static/chunks/4103-fc17f1c6d23f042f.js43 KB38 KB (91%)✓3rd
https://www.groupe-sncf.com/_next/static/chunks/534-a136d96d74e6a22a.js47 KB26 KB (58%)✓3rd
https://www.groupe-sncf.com/_next/static/chunks/1788-15deef2409962a1c.js7 KB—✓3rd
https://www.groupe-sncf.com/_next/static/chunks/4bd1b696-182b6b13bdad92e3.js55 KB—✓3rd
https://www.groupe-sncf.com/_next/static/chunks/app/error-d73583db1882fd29.js2 KB—✓3rd

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

F
Page Weight Inventory
Action
62 resources · 1.6 MB · 523 KB savings available
FIX
62 resources · 1.6 MB · 523 KB savings available
Warning::
Page weight 613 KB over 1MB target
Got: 1.6 MB Expected: ≤ 1 MB
Info::
~523 KB of savings available
Warning::
61 third-party resources (100% of weight)
Info::
1 resources over 200KB
62 resources · 1.6 MiB · 61 third-party 613.4 KiB over 1MB target
JavaScript 71% · 1.1 MiB
Image 21% · 351.9 KiB
Font 3% · 55.1 KiB
CSS 3% · 42.4 KiB
Document 2% · 25.9 KiB
Other 0% · 978 B

~523.2 KiB of savings available

Remove unused JavaScript: 523.2 KiB
F
HTTP Caching
Action
No cache headers
FIX
No cache headers
Warning::
No Cache-Control header found
Browsers will use heuristic caching, which can be unpredictable. Set explicit cache headers.

No Cache-Control header

Adding a Cache-Control header can significantly improve repeat-visit performance.

C
Page Weight Budget
Action
1.6 MB transferred, 62 requests
REVIEW
1.6 MB transferred, 62 requests
Info::
Page weighs 4.7 MB (1.6 MB transferred)
Warning::
JavaScript is 1.1 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.1 MB
Info::
62 HTTP requests
Info::
Estimated 0.34 g CO2 per page load
1.6 MB / 2.4 MB budget
1.6 MB transferred
62 requests
0.34 g CO2 per page load
JavaScript 1.1 MiB 71%
Images 349.2 KiB 21%
Fonts 55.1 KiB 3%
CSS 42.4 KiB 3%
HTML 23.7 KiB 1%
Other 4.9 KiB 0%
Other 647 B 0%
Other 331 B 0%
0 2.4 MB 4.9 MB
Approaching limit

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

B
JS Execution Cost
506ms total JS execution
REVIEW
506ms total JS execution
Info::
https://www.groupe-sncf.com/_next/static/chunks/12...: 247ms CPU time
Info::
https://www.groupe-sncf.com/_next/static/chunks/05...: 80ms CPU time
Info::
Unattributable: 70ms CPU time
Info::
https://www.groupe-sncf.com/fr: 57ms CPU time
Info::
https://js-datadome.groupe-sncf.com/tags.js: 52ms CPU time
Warning::
Third-party scripts: 506ms (100% of total)

Main Thread Breakdown

Script Evaluation 63% Script Parsing & Compilation 14% Other 11% Style & Layout 6% Parse HTML & CSS 4%
ScriptTotalScriptingParse/CompileParty
https://www.groupe-sncf.com/_next/static/chunks/1255-31341e05e682b6b5.js247ms211ms7ms3rd
https://www.groupe-sncf.com/_next/static/chunks/05f6971a-3deaa127f637de56.js80ms60ms20ms3rd
Unattributable70ms7ms0ms3rd
https://www.groupe-sncf.com/fr57ms3ms3ms3rd
https://js-datadome.groupe-sncf.com/tags.js52ms46ms2ms3rd
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

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
Image Optimization
11 images, 0 KB saveable
PASS
11 images, 0 KB saveable
Warning::
https://www.cybermalveillance.gouv.fr/medias/2021/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
11 images 349 KB
0 oversized -0 KB
1 legacy format
1 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

A+
Font Loading
4 fonts (55 KB)
PASS
4 fonts (55 KB)
Info::
4 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

4

55 KB total

Render-blocking

0

of 4

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 FCP 982 ms LCP 1.5 shttps://www.groupe-sncf.com/_next/static/media/922d67442fa2d113-s.p.woff2922d67442fa2d113-s.p.woff2 https://www.groupe-sncf.com/_next/static/media/922d67442fa2d113-s.p.woff2 — 17.8 KiB — 84 ms — font-display: swaphttps://www.groupe-sncf.com/_next/static/media/cb7985bf38fb6153-s.p.woff2cb7985bf38fb6153-s.p.woff2 https://www.groupe-sncf.com/_next/static/media/cb7985bf38fb6153-s.p.woff2 — 17.9 KiB — 97 ms — font-display: swaphttps://www.groupe-sncf.com/_next/static/media/e73a90aae6c03fa5-s.p.woff2e73a90aae6c03fa5-s.p.woff2 https://www.groupe-sncf.com/_next/static/media/e73a90aae6c03fa5-s.p.woff2 — 13.5 KiB — 98 ms — font-display: swaphttps://www.groupe-sncf.com/_next/static/media/29b0bf990024f1c7-s.woff229b0bf990024f1c7-s.woff2 https://www.groupe-sncf.com/_next/static/media/29b0bf990024f1c7-s.woff2 — 6.0 KiB — 44 ms — font-display: swap
922d67442fa2d113-s.p.woff2 woff2 swap
Size 18 KB
Load time 84 ms
Start 341 ms
Risk FOUT — text flashes from fallback to web font
cb7985bf38fb6153-s.p.woff2 woff2 swap
Size 18 KB
Load time 97 ms
Start 342 ms
Risk FOUT — text flashes from fallback to web font
e73a90aae6c03fa5-s.p.woff2 woff2 swap
Size 13 KB
Load time 98 ms
Start 343 ms
Risk FOUT — text flashes from fallback to web font
29b0bf990024f1c7-s.woff2 woff2 swap
Size 6 KB
Load time 44 ms
Start 479 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
Network Waterfall
62 requests over 1419ms
INFO
0 ms 500 ms 1.0 s 1.5 s FCP 982 ms LCP 1.5 shttps://sncf.com// https://sncf.com/ — 301 — 83 B — 60 ms — h2https://www.sncf.com/www.sncf.com/ https://www.sncf.com/ — 301 — 88 B — 56 ms — h2https://www.groupe-sncf.com/www.groupe-sncf.com/ https://www.groupe-sncf.com/ — 308 — 2.0 KiB — 137 ms — h2https://www.groupe-sncf.com/frwww.groupe-sncf.com/fr https://www.groupe-sncf.com/fr — 200 — 23.7 KiB — 80 ms — h2https://www.groupe-sncf.com/_next/static/media/922d67442fa2d113-s.p.woff2www.groupe-sncf.com/_next/static/me... https://www.groupe-sncf.com/_next/static/media/922d67442fa2d113-s.p.woff2 — 200 — 17.8 KiB — 84 ms — h3https://www.groupe-sncf.com/_next/static/media/cb7985bf38fb6153-s.p.woff2www.groupe-sncf.com/_next/static/me... https://www.groupe-sncf.com/_next/static/media/cb7985bf38fb6153-s.p.woff2 — 200 — 17.9 KiB — 97 ms — h3https://www.groupe-sncf.com/_next/static/media/e73a90aae6c03fa5-s.p.woff2www.groupe-sncf.com/_next/static/me... https://www.groupe-sncf.com/_next/static/media/e73a90aae6c03fa5-s.p.woff2 — 200 — 13.5 KiB — 98 ms — h3https://www.groupe-sncf.com/_next/static/css/77ef6fe080e86852.csswww.groupe-sncf.com/_next/static/cs... https://www.groupe-sncf.com/_next/static/css/77ef6fe080e86852.css — 200 — 19.3 KiB — 80 ms — h3https://www.groupe-sncf.com/_next/static/css/4169b9dceefac52c.csswww.groupe-sncf.com/_next/static/cs... https://www.groupe-sncf.com/_next/static/css/4169b9dceefac52c.css — 200 — 1.9 KiB — 66 ms — h3https://www.groupe-sncf.com/_next/static/css/d808df294caa8a5c.csswww.groupe-sncf.com/_next/static/cs... https://www.groupe-sncf.com/_next/static/css/d808df294caa8a5c.css — 200 — 1.9 KiB — 66 ms — h3https://www.groupe-sncf.com/_next/static/css/358e91d545ff2e24.csswww.groupe-sncf.com/_next/static/cs... https://www.groupe-sncf.com/_next/static/css/358e91d545ff2e24.css — 200 — 1.9 KiB — 46 ms — h3https://www.groupe-sncf.com/_next/static/css/6c1db005254b50e3.csswww.groupe-sncf.com/_next/static/cs... https://www.groupe-sncf.com/_next/static/css/6c1db005254b50e3.css — 200 — 4.0 KiB — 67 ms — h3https://www.groupe-sncf.com/_next/static/css/227a91527b8abe71.csswww.groupe-sncf.com/_next/static/cs... https://www.groupe-sncf.com/_next/static/css/227a91527b8abe71.css — 200 — 11.6 KiB — 81 ms — h3https://www.groupe-sncf.com/_next/static/css/b5802bc2880869ca.csswww.groupe-sncf.com/_next/static/cs... https://www.groupe-sncf.com/_next/static/css/b5802bc2880869ca.css — 200 — 1.8 KiB — 80 ms — h3https://js-datadome.groupe-sncf.com/tags.jsjs-datadome.groupe-sncf.com/tags.js https://js-datadome.groupe-sncf.com/tags.js — 200 — 40.8 KiB — 71 ms — h2https://www.groupe-sncf.com/scripts/critical-min.jswww.groupe-sncf.com/scripts/critica... https://www.groupe-sncf.com/scripts/critical-min.js — 200 — 1.9 KiB — 94 ms — h3https://www.groupe-sncf.com/_next/static/chunks/webpack-48f911772e71b9e7.jswww.groupe-sncf.com/_next/static/ch... https://www.groupe-sncf.com/_next/static/chunks/webpack-48f911772e71b9e7.js — 200 — 3.5 KiB — 52 ms — h3https://www.groupe-sncf.com/_next/static/chunks/4bd1b696-182b6b13bdad92e3.jswww.groupe-sncf.com/_next/static/ch... https://www.groupe-sncf.com/_next/static/chunks/4bd1b696-182b6b13bdad92e3.js — 200 — 54.9 KiB — 84 ms — h3https://www.groupe-sncf.com/_next/static/chunks/1255-31341e05e682b6b5.jswww.groupe-sncf.com/_next/static/ch... https://www.groupe-sncf.com/_next/static/chunks/1255-31341e05e682b6b5.js — 200 — 45.3 KiB — 96 ms — h3https://www.groupe-sncf.com/_next/static/chunks/main-app-ef3a8679441a467c.jswww.groupe-sncf.com/_next/static/ch... https://www.groupe-sncf.com/_next/static/chunks/main-app-ef3a8679441a467c.js — 200 — 1.8 KiB — 60 ms — h3https://www.groupe-sncf.com/_next/static/chunks/4909-5daf217e5b4ca788.jswww.groupe-sncf.com/_next/static/ch... https://www.groupe-sncf.com/_next/static/chunks/4909-5daf217e5b4ca788.js — 200 — 10.0 KiB — 57 ms — h3https://www.groupe-sncf.com/_next/static/chunks/5239-927756e38ffca55f.jswww.groupe-sncf.com/_next/static/ch... https://www.groupe-sncf.com/_next/static/chunks/5239-927756e38ffca55f.js — 200 — 7.0 KiB — 57 ms — h3https://www.groupe-sncf.com/_next/static/chunks/1788-15deef2409962a1c.jswww.groupe-sncf.com/_next/static/ch... https://www.groupe-sncf.com/_next/static/chunks/1788-15deef2409962a1c.js — 200 — 7.0 KiB — 54 ms — h3https://www.groupe-sncf.com/_next/static/chunks/app/error-d73583db1882fd29.jswww.groupe-sncf.com/_next/static/ch... https://www.groupe-sncf.com/_next/static/chunks/app/error-d73583db1882fd29.js — 200 — 2.0 KiB — 67 ms — h3https://www.groupe-sncf.com/_next/static/chunks/app/global-error-23cde0a43e615922.jswww.groupe-sncf.com/_next/static/ch... https://www.groupe-sncf.com/_next/static/chunks/app/global-error-23cde0a43e615922.js — 200 — 1.9 KiB — 52 ms — h3https://www.groupe-sncf.com/_next/static/chunks/05f6971a-3deaa127f637de56.jswww.groupe-sncf.com/_next/static/ch... https://www.groupe-sncf.com/_next/static/chunks/05f6971a-3deaa127f637de56.js — 200 — 258.4 KiB — 104 ms — h3https://www.groupe-sncf.com/_next/static/chunks/65fb8c99-2286602842fcc7e3.jswww.groupe-sncf.com/_next/static/ch... https://www.groupe-sncf.com/_next/static/chunks/65fb8c99-2286602842fcc7e3.js — 200 — 23.6 KiB — 104 ms — h3https://www.groupe-sncf.com/_next/static/chunks/865-2051a693686a9757.jswww.groupe-sncf.com/_next/static/ch... https://www.groupe-sncf.com/_next/static/chunks/865-2051a693686a9757.js — 200 — 31.4 KiB — 107 ms — h3https://www.groupe-sncf.com/_next/static/chunks/4103-fc17f1c6d23f042f.jswww.groupe-sncf.com/_next/static/ch... https://www.groupe-sncf.com/_next/static/chunks/4103-fc17f1c6d23f042f.js — 200 — 43.2 KiB — 108 ms — h3https://www.groupe-sncf.com/_next/static/chunks/534-a136d96d74e6a22a.jswww.groupe-sncf.com/_next/static/ch... https://www.groupe-sncf.com/_next/static/chunks/534-a136d96d74e6a22a.js — 200 — 47.2 KiB — 106 ms — h3
0 ms 500 ms 1.0 s 1.5 s FCP 982 ms LCP 1.5 shttps://sncf.com// https://sncf.com/ — 301 — 83 B — 60 ms — h2https://www.sncf.com/www.sncf.com/ https://www.sncf.com/ — 301 — 88 B — 56 ms — h2https://www.groupe-sncf.com/www.groupe-sncf.com/ https://www.groupe-sncf.com/ — 308 — 2.0 KiB — 137 ms — h2https://www.groupe-sncf.com/frwww.groupe-sncf.com/fr https://www.groupe-sncf.com/fr — 200 — 23.7 KiB — 80 ms — h2https://www.groupe-sncf.com/_next/static/media/922d67442fa2d113-s.p.woff2www.groupe-sncf.com/_next/static/me... https://www.groupe-sncf.com/_next/static/media/922d67442fa2d113-s.p.woff2 — 200 — 17.8 KiB — 84 ms — h3https://www.groupe-sncf.com/_next/static/media/cb7985bf38fb6153-s.p.woff2www.groupe-sncf.com/_next/static/me... https://www.groupe-sncf.com/_next/static/media/cb7985bf38fb6153-s.p.woff2 — 200 — 17.9 KiB — 97 ms — h3https://www.groupe-sncf.com/_next/static/media/e73a90aae6c03fa5-s.p.woff2www.groupe-sncf.com/_next/static/me... https://www.groupe-sncf.com/_next/static/media/e73a90aae6c03fa5-s.p.woff2 — 200 — 13.5 KiB — 98 ms — h3https://www.groupe-sncf.com/_next/static/css/77ef6fe080e86852.csswww.groupe-sncf.com/_next/static/cs... https://www.groupe-sncf.com/_next/static/css/77ef6fe080e86852.css — 200 — 19.3 KiB — 80 ms — h3https://www.groupe-sncf.com/_next/static/css/4169b9dceefac52c.csswww.groupe-sncf.com/_next/static/cs... https://www.groupe-sncf.com/_next/static/css/4169b9dceefac52c.css — 200 — 1.9 KiB — 66 ms — h3https://www.groupe-sncf.com/_next/static/css/d808df294caa8a5c.csswww.groupe-sncf.com/_next/static/cs... https://www.groupe-sncf.com/_next/static/css/d808df294caa8a5c.css — 200 — 1.9 KiB — 66 ms — h3https://www.groupe-sncf.com/_next/static/css/358e91d545ff2e24.csswww.groupe-sncf.com/_next/static/cs... https://www.groupe-sncf.com/_next/static/css/358e91d545ff2e24.css — 200 — 1.9 KiB — 46 ms — h3https://www.groupe-sncf.com/_next/static/css/6c1db005254b50e3.csswww.groupe-sncf.com/_next/static/cs... https://www.groupe-sncf.com/_next/static/css/6c1db005254b50e3.css — 200 — 4.0 KiB — 67 ms — h3https://www.groupe-sncf.com/_next/static/css/227a91527b8abe71.csswww.groupe-sncf.com/_next/static/cs... https://www.groupe-sncf.com/_next/static/css/227a91527b8abe71.css — 200 — 11.6 KiB — 81 ms — h3https://www.groupe-sncf.com/_next/static/css/b5802bc2880869ca.csswww.groupe-sncf.com/_next/static/cs... https://www.groupe-sncf.com/_next/static/css/b5802bc2880869ca.css — 200 — 1.8 KiB — 80 ms — h3https://js-datadome.groupe-sncf.com/tags.jsjs-datadome.groupe-sncf.com/tags.js https://js-datadome.groupe-sncf.com/tags.js — 200 — 40.8 KiB — 71 ms — h2https://www.groupe-sncf.com/scripts/critical-min.jswww.groupe-sncf.com/scripts/critica... https://www.groupe-sncf.com/scripts/critical-min.js — 200 — 1.9 KiB — 94 ms — h3https://www.groupe-sncf.com/_next/static/chunks/webpack-48f911772e71b9e7.jswww.groupe-sncf.com/_next/static/ch... 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HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
100% of JavaScript execution is third-party
First-party Third-party 506ms · 368KB · $7/mo
www.groupe-sncf.com
Other
Costly
Execution 247ms
Transfer 45 KB
Monthly Cost $3/mo
www.groupe-sncf.com
Other
Optional
Execution 80ms
Transfer 258 KB
Unused 84%
Monthly Cost $1/mo
Unattributable
Other
Optional
Execution 70ms
Transfer 0 KB
Monthly Cost $1/mo
www.groupe-sncf.com
Other
Optional
Execution 57ms
Transfer 24 KB
Monthly Cost $1/mo
js-datadome.groupe-sncf.com
Other
Optional
Execution 52ms
Transfer 41 KB
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • www.groupe-sncf.com adds 247ms and costs ~$3/month

100% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.

Why this matters

When third-party JS execution time exceeds your own, performance gains from frontend work are capped by code you don't own.

Learn more ▾

Every millisecond of third-party JS competes with your own for main-thread time. If their share is bigger than yours, optimization on your code base barely moves the needle. Audit, defer, or remove third-parties before further frontend optimization. Use Lighthouse's third-party audit to identify the worst offenders.

Source: web.dev

www.groupe-sncf.com takes 247ms 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

84% of www.groupe-sncf.com'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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