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https://tfl.gov.uk

Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
77
GRADE
C
FIX
2
REVIEW
3
PASS
8
INFO
2

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

Mobile Desktop
59
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
96
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.
77
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.

574 ms

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

3.11 s

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

478 ms

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

0.012

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

1.92 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.

3.17 s

Page Load Progression

484 ms
968 ms
1.5 s
1.9 s
2.4 s
2.9 s
3.4 s
3.9 s
Checks
15
8 PASS 3 REVIEW 2 FIX
F
JS Bundles
Action
19 scripts, 460 KB unused
FIX
19 scripts, 460 KB unused
Warning::
https://tfl.gov.uk/cdn/static/scripts/core/min/glo...: 244 KB unused (78%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://tfl.gov.uk/cdn/static/scripts/core/min/glo...: unminified — 111 KB could be saved
Warning::
https://translate.googleapis.com/_/translate_http/...: 109 KB unused (92%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://consent.cookiebot.com/Framework/IAB/consen...: 64 KB unused (73%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://consent.cookiebot.com/uc.js: 22 KB unused (63%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://consent.cookiebot.com/e601acc6-2e6f-4bed-a...: 21 KB unused (7%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 460 KB
460 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://tfl.gov.uk/cdn/static/scripts/core/min/global.min.846723f5.js313 KB244 KB (78%)✗1st
https://translate.googleapis.com/_/translate_http/_/js/k=translate_http.tr.es.eNjH1Jo6ldQ.O/am=AAAAAQ/d=1/exm=el_conf/ed=1/rs=AN8SPfq_osd-q7vwQm5aouAQRZibUmx4sg/m=el_main119 KB109 KB (92%)✓3rd
https://consent.cookiebot.com/Framework/IAB/consent-sdk-2.3.js88 KB64 KB (73%)✓3rd
https://consent.cookiebot.com/uc.js36 KB22 KB (63%)✓3rd
https://consent.cookiebot.com/e601acc6-2e6f-4bed-a826-046477b39b61/cc.js?renew=false&referer=tfl.gov.uk&dnt=false&init=false&framework=TCFv2.3300 KB21 KB (7%)✓3rd
https://tfl.gov.uk/cdn/static/scripts/jquery/1.12.4/jquery.min.js46 KB—✗1st
https://tfl.gov.uk/cdn/static/scripts//plugins/includes/jquery.signalR-2.2.0.min.js15 KB—✓1st
https://assets.adobedtm.com/extensions/EP31dbb9c60e404ba1aa6e746d49be6f29/AppMeasurement_Module_ActivityMap.min.js2 KB—✓3rd
https://tfl.gov.uk/cdn/static/scripts/plugins/smart-banner/smartbanner.js4 KB—✓1st
https://translate.google.com/translate_a/element.js?cb=googleTranslateElementInit28 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
Page Weight Inventory
Action
48 resources · 2.0 MB · 460 KB savings available
FIX
48 resources · 2.0 MB · 460 KB savings available
Warning::
Page weight 1003 KB over 1MB target
Got: 2.0 MB Expected: ≤ 1 MB
Info::
~460 KB of savings available
Info::
14 third-party resources (31% of weight)
Info::
3 resources over 200KB
48 resources · 2.0 MiB · 14 third-party 1003.1 KiB over 1MB target
JavaScript 52% · 1.0 MiB
Image 27% · 547.6 KiB
CSS 15% · 299.3 KiB
Font 5% · 96.6 KiB
Document 1% · 26.6 KiB
Other 0% · 8.1 KiB

~460.1 KiB of savings available

Remove unused JavaScript: 460.1 KiB
C
Page Weight Budget
Action
2.0 MB transferred, 48 requests
REVIEW
2.0 MB transferred, 48 requests
Info::
Page weighs 6.1 MB (2.0 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::
CSS is 299 KB — consider purging unused styles
Remove unused CSS rules with tools like PurgeCSS to reduce stylesheet size.
Got: 299 KB
Info::
48 HTTP requests
Info::
Estimated 0.42 g CO2 per page load
2.0 MB / 2.4 MB budget
2.0 MB transferred
48 requests
0.42 g CO2 per page load
JavaScript 1.0 MiB 52%
Images 546.4 KiB 27%
CSS 299.3 KiB 15%
Fonts 96.6 KiB 5%
HTML 24.3 KiB 1%
Other 10.4 KiB 1%
Other 1.2 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

Remove unused CSS rules with tools like PurgeCSS to reduce stylesheet size.

Why this matters

CSS bundle is large — purge unused styles (PurgeCSS, Tailwind JIT) to reduce CSS payload.

Source: web.dev

C
Image Optimization
Action
10 images, 0 KB saveable
REVIEW
10 images, 0 KB saveable
Warning::
https://tfl.gov.uk/static/cms/images/MoL.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://tfl.gov.uk/cdn/static/cms/images/promos/po... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://tfl.gov.uk/cdn/static/cms/images/promos/ba... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
10 images 546 KB
0 oversized -0 KB
10 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

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

Source: web.dev / Core Web Vitals

C
JS Execution Cost
Action
1544ms total JS execution
REVIEW
1544ms total JS execution
Warning::
https://consent.cookiebot.com/e601acc6-2e6f-4bed-a...: 1115ms CPU time
Info::
https://tfl.gov.uk/: 186ms CPU time
Info::
https://tfl.gov.uk/cdn/static/scripts/core/min/glo...: 184ms CPU time
Info::
Unattributable: 58ms CPU time
Warning::
Third-party scripts: 1173ms (76% of total)

Main Thread Breakdown

Parse HTML & CSS 42% Script Evaluation 34% Style & Layout 9% Other 8% Script Parsing & Compilation 6%
ScriptTotalScriptingParse/CompileParty
https://consent.cookiebot.com/e601acc6-2e6f-4bed-a826-046477b39b61/cc.js?renew=false&referer=tfl.gov.uk&dnt=false&init=false&framework=TCFv2.31115ms362ms27ms3rd
https://tfl.gov.uk/186ms9ms6ms1st
https://tfl.gov.uk/cdn/static/scripts/core/min/global.min.846723f5.js184ms100ms27ms1st
Unattributable58ms1ms0ms3rd
A
Third-Party Impact
31% third-party, 0 ms blocking
PASS
31% third-party, 0 ms blocking
Info::
Third-party code accounts for 31% of page weight (633.5 KiB of 2.0 MiB)
Info::
Third-party blocking time is low (0 ms)
69%
31%
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 (97 KB)
PASS
4 fonts (97 KB)
Info::
4 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

4

97 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 1.0 s 2.0 s 3.0 s FCP 574 ms LCP 3.1 shttps://tfl.gov.uk/cdn/static/assets/fonts/Johnston100-Light.woff2Johnston100-Light.woff2 https://tfl.gov.uk/cdn/static/assets/fonts/Johnston100-Light.woff2 — 20.9 KiB — 41 ms — font-display: swaphttps://tfl.gov.uk/cdn/static/assets/fonts/Johnston100-Regular.woff2Johnston100-Regular.woff2 https://tfl.gov.uk/cdn/static/assets/fonts/Johnston100-Regular.woff2 — 20.3 KiB — 46 ms — font-display: swaphttps://tfl.gov.uk/cdn/static/assets/fonts/Johnston100-Medium.woff2Johnston100-Medium.woff2 https://tfl.gov.uk/cdn/static/assets/fonts/Johnston100-Medium.woff2 — 20.7 KiB — 31 ms — font-display: swaphttps://tfl.gov.uk/static/1/assets/fonts/njfontsigning-medium.woffnjfontsigning-medium.woff https://tfl.gov.uk/static/1/assets/fonts/njfontsigning-medium.woff — 34.6 KiB — 31 ms — font-display: swap
Johnston100-Light.woff2 woff2 swap
Size 21 KB
Load time 41 ms
Start 267 ms
Risk FOUT — text flashes from fallback to web font
Johnston100-Regular.woff2 woff2 swap
Size 20 KB
Load time 46 ms
Start 268 ms
Risk FOUT — text flashes from fallback to web font
Johnston100-Medium.woff2 woff2 swap
Size 21 KB
Load time 31 ms
Start 268 ms
Risk FOUT — text flashes from fallback to web font
njfontsigning-medium.woff woff swap
Size 35 KB
Load time 31 ms
Start 614 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
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)

Fixing the unchecked items could save ~10 KB and ~20 ms

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

A+
HTTP Caching
max-age=60 (1 minute)
PASS
max-age=60 (1 minute)
Info::
Cache-Control header is set
Got: public, must-revalidate, max-age=60, s-maxage=60
Info::
Effective TTL: 1 minute (max-age=60)
Info::
CDN TTL: 1 minute (s-maxage=60)
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

public, must-revalidate, max-age=60, s-maxage=60

DirectiveValueMeaning
public—Any cache may store this response
must-revalidate—Must recheck with server after expiry
max-age60Cache for 1 minute
s-maxage60CDN caches for 1 minute
Effective TTL: 60 seconds
Network Waterfall
48 requests over 3858ms
INFO
0 ms 1.0 s 2.0 s 3.0 s 4.0 s FCP 574 ms LCP 3.1 shttps://tfl.gov.uk// https://tfl.gov.uk/ — 200 — 23.5 KiB — 89 ms — h2https://consent.cookiebot.com/uc.jsconsent.cookiebot.com/uc.js https://consent.cookiebot.com/uc.js — 200 — 35.7 KiB — 64 ms — h2https://assets.adobedtm.com/launch-ENc5e3f827edc94f2a816110524598acd7.min.jsassets.adobedtm.com/launch-ENc5e3f8... https://assets.adobedtm.com/launch-ENc5e3f827edc94f2a816110524598acd7.min.js — 200 — 38.4 KiB — 45 ms — h2https://tfl.gov.uk/cdn/static/styles/core/min/small.min.1d5963c4.css/cdn/static/styles/core/min/small.m... https://tfl.gov.uk/cdn/static/styles/core/min/small.min.1d5963c4.css — 200 — 91.4 KiB — 68 ms — h2https://tfl.gov.uk/cdn/static/styles/core/min/modules.min.a75e2042.css/cdn/static/styles/core/min/modules... https://tfl.gov.uk/cdn/static/styles/core/min/modules.min.a75e2042.css — 200 — 82.8 KiB — 73 ms — h2https://tfl.gov.uk/cdn/static/styles/core/min/specifics-small.min.252ae3e0.css/cdn/static/styles/core/min/specifi... https://tfl.gov.uk/cdn/static/styles/core/min/specifics-small.min.252ae3e0.css — 200 — 85.3 KiB — 78 ms — h2https://tfl.gov.uk/cdn/static/styles/core/min/medium.min.cc9ff121.css/cdn/static/styles/core/min/medium.... https://tfl.gov.uk/cdn/static/styles/core/min/medium.min.cc9ff121.css — 200 — 20.1 KiB — 80 ms — h2https://tfl.gov.uk/cdn/static/styles/core/min/large.min.c085d741.css/cdn/static/styles/core/min/large.m... https://tfl.gov.uk/cdn/static/styles/core/min/large.min.c085d741.css — 200 — 12.4 KiB — 31 ms — h2https://tfl.gov.uk/cdn/static/cms/images/promos/tfl-go-hp_rdax_400x200.png/cdn/static/cms/images/promos/tfl-g... https://tfl.gov.uk/cdn/static/cms/images/promos/tfl-go-hp_rdax_400x200.png — 200 — 20.7 KiB — 79 ms — h2https://tfl.gov.uk/cdn/static/cms/images/promos/pom-pom-london-tfl-collection_rdax_400x200.png/cdn/static/cms/images/promos/pom-p... https://tfl.gov.uk/cdn/static/cms/images/promos/pom-pom-london-tfl-collection_rdax_400x200.png — 200 — 93.9 KiB — 79 ms — h2https://consentcdn.cookiebot.com/consentconfig/e601acc6-2e6f-4bed-a826-046477b39b61/settings.jsonconsentcdn.cookiebot.com/consentcon... https://consentcdn.cookiebot.com/consentconfig/e601acc6-2e6f-4bed-a826-046477b39b61/settings.json — 200 — 948 B — 44 ms — h2https://tfl.gov.uk/cdn/static/cms/images/promos/bank-closure-700x350_rdax_400x200s.jpg/cdn/static/cms/images/promos/bank-... https://tfl.gov.uk/cdn/static/cms/images/promos/bank-closure-700x350_rdax_400x200s.jpg — 200 — 36.8 KiB — 29 ms — h2https://tfl.gov.uk/static/cms/images/MoL.png/static/cms/images/MoL.png https://tfl.gov.uk/static/cms/images/MoL.png — 200 — 1.8 KiB — 30 ms — h2https://tfl.gov.uk/static/cms/images/GLA_Logo.png/static/cms/images/GLA_Logo.png https://tfl.gov.uk/static/cms/images/GLA_Logo.png — 200 — 2.0 KiB — 31 ms — h2https://tfl.gov.uk/cdn/static/scripts/core/min/init.min.347d0889.js/cdn/static/scripts/core/min/init.m... https://tfl.gov.uk/cdn/static/scripts/core/min/init.min.347d0889.js — 200 — 10.7 KiB — 36 ms — h2https://translate.google.com/translate_a/element.js?cb=googleTranslateElementInittranslate.google.com/translate_a/el... https://translate.google.com/translate_a/element.js?cb=googleTranslateElementInit — 200 — 28.3 KiB — 108 ms — h2https://tfl.gov.uk/cdn/static/scripts/jquery/1.12.4/jquery.min.js/cdn/static/scripts/jquery/1.12.4/j... https://tfl.gov.uk/cdn/static/scripts/jquery/1.12.4/jquery.min.js — 200 — 46.4 KiB — 39 ms — h2https://tfl.gov.uk/cdn/static/scripts/plugins/smart-banner/smartbanner.js/cdn/static/scripts/plugins/smart-b... https://tfl.gov.uk/cdn/static/scripts/plugins/smart-banner/smartbanner.js — 200 — 4.5 KiB — 37 ms — h2https://tfl.gov.uk/cdn/static/images/MoL-small.png/cdn/static/images/MoL-small.png https://tfl.gov.uk/cdn/static/images/MoL-small.png — 200 — 1.4 KiB — 33 ms — h2https://assets.adobedtm.com/extensions/EP31dbb9c60e404ba1aa6e746d49be6f29/AppMeasurement.min.jsassets.adobedtm.com/extensions/EP31... https://assets.adobedtm.com/extensions/EP31dbb9c60e404ba1aa6e746d49be6f29/AppMeasurement.min.js — 200 — 13.0 KiB — 5 ms — h2https://assets.adobedtm.com/extensions/EP31dbb9c60e404ba1aa6e746d49be6f29/AppMeasurement_Module_ActivityMap.min.jsassets.adobedtm.com/extensions/EP31... https://assets.adobedtm.com/extensions/EP31dbb9c60e404ba1aa6e746d49be6f29/AppMeasurement_Module_ActivityMap.min.js — 200 — 1.8 KiB — 6 ms — h2https://consent.cookiebot.com/Framework/IAB/consent-sdk-2.3.jsconsent.cookiebot.com/Framework/IAB... https://consent.cookiebot.com/Framework/IAB/consent-sdk-2.3.js — 200 — 87.9 KiB — 12 ms — h2https://consent.cookiebot.com/e601acc6-2e6f-4bed-a826-046477b39b61/cc.js?renew=false&referer=tfl.gov.uk&dnt=false&init=false&framework=TCFv2.3consent.cookiebot.com/e601acc6-2e6f... https://consent.cookiebot.com/e601acc6-2e6f-4bed-a826-046477b39b61/cc.js?renew=false&referer=tfl.gov.uk&dnt=false&init=false&framework=TCFv2.3 — 200 — 300.1 KiB — 162 ms — h2https://tfl.gov.uk/cdn/static/styles/core/min/print.min.2dbbc696.css/cdn/static/styles/core/min/print.m... https://tfl.gov.uk/cdn/static/styles/core/min/print.min.2dbbc696.css — 200 — 2.6 KiB — 31 ms — h2https://tfl.gov.uk/static/1/images/vsprite_x2.34614087.png/static/1/images/vsprite_x2.3461408... https://tfl.gov.uk/static/1/images/vsprite_x2.34614087.png — 200 — 249.4 KiB — 40 ms — h2https://tfl.gov.uk/static/1/images/homepage_sprite_x2.png/static/1/images/homepage_sprite_x2... https://tfl.gov.uk/static/1/images/homepage_sprite_x2.png — 200 — 24.7 KiB — 27 ms — h2https://tfl.gov.uk/cdn/static/assets/fonts/Johnston100-Light.woff2/cdn/static/assets/fonts/Johnston10... https://tfl.gov.uk/cdn/static/assets/fonts/Johnston100-Light.woff2 — 200 — 20.9 KiB — 41 ms — h2https://tfl.gov.uk/cdn/static/assets/fonts/Johnston100-Regular.woff2/cdn/static/assets/fonts/Johnston10... https://tfl.gov.uk/cdn/static/assets/fonts/Johnston100-Regular.woff2 — 200 — 20.3 KiB — 46 ms — h2https://tfl.gov.uk/cdn/static/assets/fonts/Johnston100-Medium.woff2/cdn/static/assets/fonts/Johnston10... https://tfl.gov.uk/cdn/static/assets/fonts/Johnston100-Medium.woff2 — 200 — 20.7 KiB — 31 ms — h2https://consentcdn.cookiebot.com/sdk/bc-v4.min.htmlconsentcdn.cookiebot.com/sdk/bc-v4.... https://consentcdn.cookiebot.com/sdk/bc-v4.min.html — 200 — 809 B — 24 ms — h2
0 ms 1.0 s 2.0 s 3.0 s 4.0 s FCP 574 ms LCP 3.1 shttps://tfl.gov.uk// https://tfl.gov.uk/ — 200 — 23.5 KiB — 89 ms — h2https://consent.cookiebot.com/uc.jsconsent.cookiebot.com/uc.js https://consent.cookiebot.com/uc.js — 200 — 35.7 KiB — 64 ms — h2https://assets.adobedtm.com/launch-ENc5e3f827edc94f2a816110524598acd7.min.jsassets.adobedtm.com/launch-ENc5e3f8... https://assets.adobedtm.com/launch-ENc5e3f827edc94f2a816110524598acd7.min.js — 200 — 38.4 KiB — 45 ms — h2https://tfl.gov.uk/cdn/static/styles/core/min/small.min.1d5963c4.css/cdn/static/styles/core/min/small.m... https://tfl.gov.uk/cdn/static/styles/core/min/small.min.1d5963c4.css — 200 — 91.4 KiB — 68 ms — h2https://tfl.gov.uk/cdn/static/styles/core/min/modules.min.a75e2042.css/cdn/static/styles/core/min/modules... https://tfl.gov.uk/cdn/static/styles/core/min/modules.min.a75e2042.css — 200 — 82.8 KiB — 73 ms — h2https://tfl.gov.uk/cdn/static/styles/core/min/specifics-small.min.252ae3e0.css/cdn/static/styles/core/min/specifi... 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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
76% of JavaScript execution is third-party
First-party Third-party 1173ms · 300KB · £12/mo
consent.cookiebot.com
Other
Costly
Execution 1115ms
Transfer 300 KB
Unused 7%
Monthly Cost £12/mo
Unattributable
Other
Optional
Execution 58ms
Transfer 0 KB
Monthly Cost £1/mo

These scripts may cost more than they're worth

  • consent.cookiebot.com adds 1115ms and costs ~£12/month

76% 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.

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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

consent.cookiebot.com takes 1115ms 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

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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