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https://www.blablacar.fr

Performance

· 16 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
75
GRADE
C
FIX
5
REVIEW
1
PASS
8
INFO
2

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

Mobile Desktop
39
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.

2.22 s

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

16.05 s

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

2.04 s

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

0.010

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

6.20 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.

16.46 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
8 PASS 1 REVIEW 5 FIX
D
Page Weight Budget
Action
2.4 MB transferred, 78 requests
FIX
2.4 MB transferred, 78 requests
Info::
Page weighs 9.2 MB (2.4 MB transferred)
Warning::
JavaScript is 1.6 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.6 MB
Info::
78 HTTP requests
Info::
Estimated 0.50 g CO2 per page load
2.4 MB / 2.4 MB budget
2.4 MB transferred
78 requests
0.50 g CO2 per page load
JavaScript 1.6 MiB 68%
Images 523.3 KiB 22%
Fonts 174.6 KiB 7%
CSS 45.9 KiB 2%
HTML 20.4 KiB 1%
Other 4.8 KiB 0%
Other 3.0 KiB 0%
Other 1.2 KiB 0%
Other 681 B 0%
Other 0 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

D
Third-Party Impact
Action
99% third-party, 0 ms blocking
FIX
99% third-party, 0 ms blocking
Warning::
Third-party code accounts for 99% of page weight (2.3 MiB of 2.4 MiB)
Info::
Third-party blocking time is low (0 ms)
99%
First-party Third-party
F
JS Execution Cost
Action
5579ms total JS execution
FIX
5579ms total JS execution
Warning::
https://cdn.blablacar.com/k/a/6215.6f0cd314c52834b...: 1587ms CPU time
Warning::
https://cdn.blablacar.com/k/a/index.59085c37e31fdd...: 865ms CPU time
Warning::
https://www.blablacar.fr/: 759ms CPU time
Warning::
Unattributable: 660ms CPU time
Warning::
https://ddome-tag.blablacar.com/tags.js: 290ms CPU time
Warning::
Third-party scripts: 4820ms (86% of total)

Main Thread Breakdown

Script Evaluation 58% Other 16% Script Parsing & Compilation 13% Style & Layout 5% Rendering 3% Garbage Collection 3%
ScriptTotalScriptingParse/CompileParty
https://cdn.blablacar.com/k/a/6215.6f0cd314c52834b7.js1587ms1218ms154ms3rd
https://cdn.blablacar.com/k/a/index.59085c37e31fdd97.js865ms576ms272ms3rd
https://www.blablacar.fr/759ms52ms7ms1st
Unattributable660ms101ms0ms3rd
https://ddome-tag.blablacar.com/tags.js290ms252ms14ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-TVPFSZ284ms230ms51ms3rd
https://sdk.privacy-center.org/sdk/c8e2e67c354c0d6dec2981e079061b37f6a1f337/modern/sdk.c8e2e67c354c0d6dec2981e079061b37f6a1f337.js206ms168ms37ms3rd
https://sdk.privacy-center.org/sdk/c8e2e67c354c0d6dec2981e079061b37f6a1f337/modern/ui-web-en-web.c8e2e67c354c0d6dec2981e079061b37f6a1f337.js204ms139ms22ms3rd
https://cdn.blablacar.com/k/a/intl-locale.4cdbb20b883ba444.chunk.js183ms172ms6ms3rd
https://cdn.blablacar.com/k/a/9245.708db02cfe26ed36.chunk.js178ms128ms25ms3rd

Showing top 10 of 13 scripts

F
JS Bundles
Action
31 scripts, 656 KB unused
FIX
31 scripts, 656 KB unused
Warning::
https://cdn.blablacar.com/k/a/6215.6f0cd314c52834b...: 246 KB unused (60%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.blablacar.com/k/a/index.59085c37e31fdd...: 218 KB unused (50%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-TVP...: 79 KB unused (45%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.blablacar.com/k/a/6187.cab3118d515f4ea...: 48 KB unused (73%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://sdk.privacy-center.org/sdk/c8e2e67c354c0d6...: 44 KB unused (50%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 656 KB
656 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://cdn.blablacar.com/k/a/6215.6f0cd314c52834b7.js410 KB246 KB (60%)✓3rd
https://cdn.blablacar.com/k/a/index.59085c37e31fdd97.js436 KB218 KB (50%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-TVPFSZ175 KB79 KB (45%)✓3rd
https://cdn.blablacar.com/k/a/6187.cab3118d515f4ea4.chunk.js66 KB48 KB (73%)✓3rd
https://sdk.privacy-center.org/sdk/c8e2e67c354c0d6dec2981e079061b37f6a1f337/modern/sdk.c8e2e67c354c0d6dec2981e079061b37f6a1f337.js90 KB44 KB (50%)✓3rd
https://try.abtasty.com/8c952bdd9cb88033ffef07632e185107/main.51be40c215b8bdf2eeec.js46 KB20 KB (44%)✓3rd
https://cdn.blablacar.com/k/a/6566.a3f35027a152c29b.chunk.js4 KB—✓3rd
https://cdn.blablacar.com/k/a/5168.871296c462df99ba.chunk.js2 KB—✓3rd
https://cdn.blablacar.com/k/a/7663.0735c7dfe8c4449e.chunk.js3 KB—✓3rd
https://cdn.blablacar.com/k/a/1237.5d60fe73894ef6ad.chunk.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

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
Image Optimization
Action
11 images, 0 KB saveable
REVIEW
11 images, 0 KB saveable
Warning::
https://cdn.blablacar.com/k/a/images/train-ddad238... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdn.blablacar.com/didomi/blablacar-logo-2.... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
11 images 523 KB
0 oversized -0 KB
5 legacy format
2 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

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
3 fonts (175 KB)
PASS
3 fonts (175 KB)
Info::
3 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

3

175 KB total

Render-blocking

0

of 3

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 14.0 s 16.0 s FCP 2.2 s LCP 16.0 shttps://cdn.blablacar.com/kairos/theme-provider/assets/fonts/GT-Eesti-Pro-Display-Medium-1.woff2GT-Eesti-Pro-Display-Me... https://cdn.blablacar.com/kairos/theme-provider/assets/fonts/GT-Eesti-Pro-Display-Medium-1.woff2 — 59.2 KiB — 0 ms — font-display: swaphttps://cdn.blablacar.com/kairos/theme-provider/assets/fonts/GT-Eesti-Pro-Display-Regular-1.woff2GT-Eesti-Pro-Display-Re... https://cdn.blablacar.com/kairos/theme-provider/assets/fonts/GT-Eesti-Pro-Display-Regular-1.woff2 — 56.4 KiB — 0 ms — font-display: swaphttps://cdn.blablacar.com/kairos/theme-provider/assets/fonts/GT-Eesti-Pro-Display-UBold.woff2GT-Eesti-Pro-Display-UB... https://cdn.blablacar.com/kairos/theme-provider/assets/fonts/GT-Eesti-Pro-Display-UBold.woff2 — 59.0 KiB — 0 ms — font-display: swap
GT-Eesti-Pro-Display-Me... woff2 swap
Size 59 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
GT-Eesti-Pro-Display-Re... woff2 swap
Size 56 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
GT-Eesti-Pro-Display-UB... woff2 swap
Size 59 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
9 hints, 0 missing preconnects
PASS
9 hints, 0 missing preconnects
Info::
Page uses 9 resource hint(s)

Current Resource Hints

preconnect
2
preload
7
dns-prefetch
—
prefetch
—

9 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: Google Cloud

Network Waterfall
78 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
86% of JavaScript execution is third-party
First-party Third-party 4820ms · 1476KB · €52/mo
cdn.blablacar.com
Other
Costly
Execution 1587ms
Transfer 410 KB
Unused 60%
Monthly Cost €17/mo
cdn.blablacar.com
Other
Costly
Execution 865ms
Transfer 436 KB
Unused 50%
Monthly Cost €9/mo
Unattributable
Other
Costly
Execution 660ms
Transfer 0 KB
Monthly Cost €7/mo
ddome-tag.blablacar.com
Other
Costly
Execution 290ms
Transfer 43 KB
Monthly Cost €3/mo
Google Tag Manager
Tag Manager
Costly
Execution 284ms
Transfer 175 KB
Unused 45%
Monthly Cost €3/mo
sdk.privacy-center.org
Other
Costly
Execution 206ms
Transfer 90 KB
Unused 50%
Monthly Cost €2/mo
sdk.privacy-center.org
Other
Costly
Execution 204ms
Transfer 52 KB
Monthly Cost €2/mo
cdn.blablacar.com
Other
Optional
Execution 183ms
Transfer 17 KB
Monthly Cost €2/mo
cdn.blablacar.com
Other
Optional
Execution 178ms
Transfer 31 KB
Monthly Cost €2/mo
cdn.blablacar.com
Other
Optional
Execution 154ms
Transfer 66 KB
Unused 73%
Monthly Cost €2/mo
cdn.blablacar.com
Other
Optional
Execution 122ms
Transfer 111 KB
Monthly Cost €1/mo
try.abtasty.com
Other
Optional
Execution 88ms
Transfer 46 KB
Unused 44%
Monthly Cost €1/mo

These scripts may cost more than they're worth

  • cdn.blablacar.com adds 1587ms and costs ~€17/month
  • cdn.blablacar.com adds 865ms and costs ~€9/month
  • Unattributable adds 660ms and costs ~€7/month
  • ddome-tag.blablacar.com adds 290ms and costs ~€3/month
  • Google Tag Manager adds 284ms and costs ~€3/month
  • sdk.privacy-center.org adds 206ms and costs ~€2/month
  • sdk.privacy-center.org adds 204ms and costs ~€2/month

86% 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

cdn.blablacar.com takes 1587ms 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

60% of cdn.blablacar.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

cdn.blablacar.com takes 865ms 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

50% of cdn.blablacar.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

Unattributable takes 660ms 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

ddome-tag.blablacar.com takes 290ms 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

Google Tag Manager takes 284ms 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

sdk.privacy-center.org takes 206ms 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

sdk.privacy-center.org takes 204ms 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

73% of cdn.blablacar.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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