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https://www.sncf-connect.com

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
84
GRADE
B
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.
97
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.

722 ms

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

2.11 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.

0.102

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

986 ms

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

2.11 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
JS Bundles
Action
23 scripts, 363 KB unused
FIX
23 scripts, 363 KB unused
Warning::
https://www.sncf-connect.com/widget/web-widgets-v1...: 154 KB unused (51%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://securepubads.g.doubleclick.net/pagead/mana...: 128 KB unused (70%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.datadoghq-browser-agent.com/eu1/v6/dat...: 46 KB unused (80%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://didomi.sncf-connect.com/sdk/c8e2e67c354c0d...: 34 KB unused (38%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 363 KB
363 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.sncf-connect.com/widget/web-widgets-v1.0.0.js304 KB154 KB (51%)✓1st
https://securepubads.g.doubleclick.net/pagead/managed/js/gpt/m202604030101/pubads_impl.js?cb=31097650183 KB128 KB (70%)✓3rd
https://www.datadoghq-browser-agent.com/eu1/v6/datadog-rum.js58 KB46 KB (80%)✓3rd
https://didomi.sncf-connect.com/sdk/c8e2e67c354c0d6dec2981e079061b37f6a1f337/modern/sdk.c8e2e67c354c0d6dec2981e079061b37f6a1f337.js90 KB34 KB (38%)✓3rd
https://www.sncf-connect.com/assets/asset_injector/js/op_festivals_ete-5d4e072bc1616bb010d062287615a45b.js?tcih7w0 KB—✓1st
https://www.sncf-connect.com/assets/js/js_hh3IOHrfXEGTLVkkuLgwMLwoBTx_6XjxOSDEjynXq9o.js?scope=footer&delta=7&language=fr-FR&theme=mercure_sb&include=eJxtkFGOwzAIRC9Ub45kEZs6bglUgFP19kuk_YhX_bHlNzMYADP03PmBxUWXh_3IK9_RvB9AltHxtqOWoZhtXaBOL3LUNCwOhn0yFuADLJkDV9A6S1rTS6WO4lfeSFagiHyoc7sqG6qkiEl8RVeBgNuAhsne3UvYJhFblGPxXqbWdrQtgQamiVtRIZpr2B7GtALzP85QnsFnOFo7Fyd8NjvNPLgfqHaOh6Blu2rvXhv6GfEvmKR1vh1W8iryjMUsf3esEO-d6BeuJa6v10 KB—✓1st
https://www.sncf-connect.com/assets/js/js_Zp0AWycn6jvnEUkHjUeCKEtXrHRBw-ZAhDXBzkjzqB0.js?scope=footer&delta=0&language=fr-FR&theme=mercure_sb&include=eJxtkFGOwzAIRC9Ub45kEZs6bglUgFP19kuk_YhX_bHlNzMYADP03PmBxUWXh_3IK9_RvB9AltHxtqOWoZhtXaBOL3LUNCwOhn0yFuADLJkDV9A6S1rTS6WO4lfeSFagiHyoc7sqG6qkiEl8RVeBgNuAhsne3UvYJhFblGPxXqbWdrQtgQamiVtRIZpr2B7GtALzP85QnsFnOFo7Fyd8NjvNPLgfqHaOh6Blu2rvXhv6GfEvmKR1vh1W8iryjMUsf3esEO-d6BeuJa6v1 KB—✓1st
https://www.sncf-connect.com/themes/custom/mercure_sb/dist/js/00-base/global/widget-cart-init.js?tcih7w0 KB—✓1st
https://www.sncf-connect.com/themes/custom/mercure_sb/dist/js/00-base/global/widget-login-init.js?tcih7w0 KB—✓1st
https://www.sncf-connect.com/assets/js/js_GPvrhW60mafr0YU742BMfwPu569xjJXhcNVbwO6YHTM.js?scope=footer&delta=3&language=fr-FR&theme=mercure_sb&include=eJxtkFGOwzAIRC9Ub45kEZs6bglUgFP19kuk_YhX_bHlNzMYADP03PmBxUWXh_3IK9_RvB9AltHxtqOWoZhtXaBOL3LUNCwOhn0yFuADLJkDV9A6S1rTS6WO4lfeSFagiHyoc7sqG6qkiEl8RVeBgNuAhsne3UvYJhFblGPxXqbWdrQtgQamiVtRIZpr2B7GtALzP85QnsFnOFo7Fyd8NjvNPLgfqHaOh6Blu2rvXhv6GfEvmKR1vh1W8iryjMUsf3esEO-d6BeuJa6v6 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

D
HTTP Caching
Action
no-store (uncacheable)
FIX
no-store (uncacheable)
Info::
Cache-Control: no-store prevents all caching
Intentional for dynamic content, but increases server load for every page view.
Got: max-age=0, private, no-cache, no-store, must-revalidate
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

max-age=0, private, no-cache, no-store, must-revalidate

DirectiveValueMeaning
max-age0Cache for 0 seconds
private—Only browser cache, not CDN/proxy
no-cache—Cache but always revalidate first
no-store—Never cache this response
must-revalidate—Must recheck with server after expiry
C
Page Weight Budget
Action
1.7 MB transferred, 57 requests
REVIEW
1.7 MB transferred, 57 requests
Info::
Page weighs 4.8 MB (1.7 MB transferred)
Warning::
JavaScript is 968 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 968 KB
Info::
57 HTTP requests
Info::
Estimated 0.35 g CO2 per page load
1.7 MB / 2.4 MB budget
1.7 MB transferred
57 requests
0.35 g CO2 per page load
JavaScript 968.1 KiB 57%
Images 480.1 KiB 28%
Fonts 100.3 KiB 6%
CSS 76.5 KiB 4%
HTML 43.5 KiB 3%
Other 29.1 KiB 2%
Other 3.3 KiB 0%
Other 3.0 KiB 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
Image Optimization
10 images, 0 KB saveable
REVIEW
10 images, 0 KB saveable
Warning::
https://www.sncf-connect.com/didomi-popin-handshak... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.sncf-connect.com/# is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
10 images 480 KB
0 oversized -0 KB
2 legacy format
3 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

Performance issues directly impact user engagement and conversion rates.

B
JS Execution Cost
994ms total JS execution
REVIEW
994ms total JS execution
Info::
Unattributable: 243ms CPU time
Info::
https://www.sncf-connect.com/widget/web-widgets-v1...: 211ms CPU time
Info::
https://www.sncf-connect.com/: 150ms CPU time
Info::
https://dd.sncf-connect.com/tags.js: 138ms CPU time
Info::
https://securepubads.g.doubleclick.net/pagead/mana...: 121ms CPU time
Warning::
Third-party scripts: 633ms (64% of total)

Main Thread Breakdown

Script Evaluation 55% Other 19% Style & Layout 10% Script Parsing & Compilation 8% Garbage Collection 5%
ScriptTotalScriptingParse/CompileParty
Unattributable243ms47ms0ms3rd
https://www.sncf-connect.com/widget/web-widgets-v1.0.0.js211ms150ms34ms1st
https://www.sncf-connect.com/150ms17ms3ms1st
https://dd.sncf-connect.com/tags.js138ms118ms3ms3rd
https://securepubads.g.doubleclick.net/pagead/managed/js/gpt/m202604030101/pubads_impl.js?cb=31097650121ms104ms16ms3rd
https://didomi.sncf-connect.com/sdk/c8e2e67c354c0d6dec2981e079061b37f6a1f337/modern/sdk.c8e2e67c354c0d6dec2981e079061b37f6a1f337.js79ms65ms8ms3rd
https://tags.tiqcdn.com/utag/e-voyageurs-sncf/s2s/prod/utag.js52ms42ms3ms3rd
A
Third-Party Impact
32% third-party, 0 ms blocking
PASS
32% third-party, 0 ms blocking
Info::
Third-party code accounts for 32% of page weight (549.3 KiB of 1.7 MiB)
Info::
Third-party blocking time is low (0 ms)
68%
32%
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
4 fonts (100 KB)
PASS
4 fonts (100 KB)
Info::
4 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

4

100 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 2.0 s FCP 722 ms LCP 2.1 shttps://www.sncf-connect.com/themes/custom/mercure_sb/dist/fonts/AvenirMedium.woff2AvenirMedium.woff2 https://www.sncf-connect.com/themes/custom/mercure_sb/dist/fonts/AvenirMedium.woff2 — 11.1 KiB — 0 ms — font-display: swaphttps://www.sncf-connect.com/themes/custom/mercure_sb/dist/fonts/AchemineBold.woff2AchemineBold.woff2 https://www.sncf-connect.com/themes/custom/mercure_sb/dist/fonts/AchemineBold.woff2 — 19.6 KiB — 0 ms — font-display: swaphttps://www.sncf-connect.com/themes/custom/mercure_sb/dist/fonts/AvenirNextRoundedProBold.woff2AvenirNextRoundedProBol... https://www.sncf-connect.com/themes/custom/mercure_sb/dist/fonts/AvenirNextRoundedProBold.woff2 — 28.2 KiB — 0 ms — font-display: swaphttps://www.sncf-connect.com/themes/custom/mercure_sb/dist/fonts/AvenirHeavy.woff2AvenirHeavy.woff2 https://www.sncf-connect.com/themes/custom/mercure_sb/dist/fonts/AvenirHeavy.woff2 — 41.4 KiB — 0 ms — font-display: swap
AvenirMedium.woff2 woff2 swap
Size 11 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
AchemineBold.woff2 woff2 swap
Size 20 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
AvenirNextRoundedProBol... woff2 swap
Size 28 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
AvenirHeavy.woff2 woff2 swap
Size 41 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: Cloudflare

Network Waterfall
57 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
64% of JavaScript execution is third-party
First-party Third-party 633ms · 333KB · $8/mo
Unattributable
Other
Costly
Execution 243ms
Transfer 0 KB
Monthly Cost $3/mo
dd.sncf-connect.com
Other
Optional
Execution 138ms
Transfer 43 KB
Monthly Cost $2/mo
securepubads.g.doubleclick.net
Other
Optional
Execution 121ms
Transfer 183 KB
Unused 70%
Monthly Cost $2/mo
didomi.sncf-connect.com
Other
Optional
Execution 79ms
Transfer 90 KB
Unused 38%
Monthly Cost $1/mo
tags.tiqcdn.com
Other
Optional
Execution 52ms
Transfer 18 KB
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • Unattributable adds 243ms and costs ~$3/month

64% 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 243ms 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

70% of securepubads.g.doubleclick.net'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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