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https://www.gov.uk

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
97
GRADE
A+
FIX
0
REVIEW
2
PASS
11
INFO
1

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

Mobile Desktop
100
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.

361 ms

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

375 ms

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

0 ms

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

0.000

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

361 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.

376 ms

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
11 PASS 2 REVIEW
B
Image Optimization
6 images, 0 KB saveable
REVIEW
6 images, 0 KB saveable
Info::
All images are well-optimized
6 images 24 KB
0 oversized -0 KB
6 legacy format
0 missing dimensions CLS risk
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Page Weight Budget
196 KB transferred, 17 requests
PASS
196 KB transferred, 17 requests
Info::
Page weighs 749 KB (196 KB transferred)
Info::
17 HTTP requests
Info::
Estimated 0.04 g CO2 per page load
196 KB / 2.4 MB budget
196 KB transferred
17 requests
0.04 g CO2 per page load
Fonts 64.1 KiB 33%
JavaScript 54.7 KiB 28%
CSS 38.5 KiB 20%
Images 24.1 KiB 12%
HTML 13.4 KiB 7%
Other 1.2 KiB 1%
0 2.4 MB 4.9 MB
Under budget
A+
Third-Party Impact
No third-party resources
PASS
No third-party resources
Info::
No third-party resources detected
No third-party resources detected — all resources are first-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+
JS Execution Cost
57ms total JS execution
PASS
57ms total JS execution
Info::
https://www.gov.uk/: 57ms CPU time

Main Thread Breakdown

Other 36% Style & Layout 28% Script Evaluation 26% Parse HTML & CSS 6% Rendering 4%
ScriptTotalScriptingParse/CompileParty
https://www.gov.uk/57ms2ms0ms1st
A+
Font Loading
2 fonts (64 KB)
PASS
2 fonts (64 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

64 KB total

Render-blocking

0

of 2

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s FCP 361 ms LCP 375 mshttps://www.gov.uk/assets/frontend/bold-b542beb274-v2-35bf540bb39615b6a517986f3aa83f7fefa1efd1878603eeeb196488078542d1.woff2bold-b542beb274-v2-35bf... https://www.gov.uk/assets/frontend/bold-b542beb274-v2-35bf540bb39615b6a517986f3aa83f7fefa1efd1878603eeeb196488078542d1.woff2 — 31.1 KiB — 10 ms — font-display: swaphttps://www.gov.uk/assets/frontend/light-94a07e06a1-v2-01565b0034e61d4609689bbb7ae0be844701f3812c8fe029fa1659b7ef3aa94f.woff2light-94a07e06a1-v2-015... https://www.gov.uk/assets/frontend/light-94a07e06a1-v2-01565b0034e61d4609689bbb7ae0be844701f3812c8fe029fa1659b7ef3aa94f.woff2 — 33.0 KiB — 9 ms — font-display: swap
bold-b542beb274-v2-35bf... woff2 swap
Size 31 KB
Load time 10 ms
Start 134 ms
Risk FOUT — text flashes from fallback to web font
light-94a07e06a1-v2-015... woff2 swap
Size 33 KB
Load time 9 ms
Start 135 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+
JS Bundles
5 scripts, 0 KB unused
PASS
5 scripts, 0 KB unused
0 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.gov.uk/assets/frontend/govuk_publishing_components/vendor/lux/lux-measurer-d66192b1b665d415e1874e49a48138b7ae339548aa6cdb8687c7f9933e72b969.js1 KB—✓1st
https://www.gov.uk/assets/frontend/govuk_publishing_components/rum-custom-data-b9e1806d1da2fa8ef1855d01aa71ba5eb0afc010dd2c4de3672cc7c7a39b0c8c.js0 KB—✓1st
https://www.gov.uk/assets/frontend/govuk_publishing_components/rum-loader-a65b10e18ceeba3bd8a2eac507c7f2c513cdc82f35097df903fdea87f1dc2e33.js1 KB—✓1st
https://www.gov.uk/assets/frontend/govuk_publishing_components/load-analytics-7796c7fd51ab494d559ba9374e4fea61a2d4fbffa3d3727da6c5026dd8808a21.js12 KB—✓1st
https://www.gov.uk/assets/frontend/application-760b7ab26c68ec64b1ac8d1645828bf46aef2dec8a9f0611ca03aaca505e53ba.js41 KB—✓1st
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+
Page Weight Inventory
17 resources · 196 KB · 0 KB savings available
PASS
17 resources · 196 KB · 0 KB savings available
Info::
Within 1MB page-weight target
Got: 196 KB
17 resources · 195.8 KiB · 0 third-party Within 1MB page-weight target
Font 33% · 64.1 KiB
JavaScript 28% · 54.7 KiB
CSS 20% · 38.5 KiB
Image 13% · 25.3 KiB
Document 7% · 13.4 KiB
A+
HTTP Caching
max-age=300 (5 minutes)
PASS
max-age=300 (5 minutes)
Info::
Cache-Control header is set
Got: max-age=300, public
Info::
Effective TTL: 5 minutes (max-age=300)
Info::
ETag present — enables conditional (304) responses
Cache-Control

max-age=300, public

DirectiveValueMeaning
max-age300Cache for 5 minutes
public—Any cache may store this response
Effective TTL: 300 seconds
Network Waterfall
17 requests over 169ms
INFO
0 ms 200 ms FCP 361 ms LCP 375 mshttps://www.gov.uk// https://www.gov.uk/ — 200 — 13.4 KiB — 31 ms — h2https://www.gov.uk/assets/frontend/views/_homepage-64a9f4f542bbda5bcdae1df09ea442583c3981460eb5cd3be12e18ba1885ba31.css/assets/frontend/views/_homepage-64... https://www.gov.uk/assets/frontend/views/_homepage-64a9f4f542bbda5bcdae1df09ea442583c3981460eb5cd3be12e18ba1885ba31.css — 200 — 1.6 KiB — 4 ms — h2https://www.gov.uk/assets/frontend/govuk_publishing_components/vendor/lux/lux-measurer-d66192b1b665d415e1874e49a48138b7ae339548aa6cdb8687c7f9933e72b969.js/assets/frontend/govuk_publishing_c... https://www.gov.uk/assets/frontend/govuk_publishing_components/vendor/lux/lux-measurer-d66192b1b665d415e1874e49a48138b7ae339548aa6cdb8687c7f9933e72b969.js — 200 — 834 B — 5 ms — h2https://www.gov.uk/assets/frontend/govuk_publishing_components/rum-custom-data-b9e1806d1da2fa8ef1855d01aa71ba5eb0afc010dd2c4de3672cc7c7a39b0c8c.js/assets/frontend/govuk_publishing_c... https://www.gov.uk/assets/frontend/govuk_publishing_components/rum-custom-data-b9e1806d1da2fa8ef1855d01aa71ba5eb0afc010dd2c4de3672cc7c7a39b0c8c.js — 200 — 331 B — 11 ms — h2https://www.gov.uk/assets/frontend/govuk_publishing_components/rum-loader-a65b10e18ceeba3bd8a2eac507c7f2c513cdc82f35097df903fdea87f1dc2e33.js/assets/frontend/govuk_publishing_c... https://www.gov.uk/assets/frontend/govuk_publishing_components/rum-loader-a65b10e18ceeba3bd8a2eac507c7f2c513cdc82f35097df903fdea87f1dc2e33.js — 200 — 610 B — 10 ms — h2https://www.gov.uk/assets/frontend/govuk_publishing_components/load-analytics-7796c7fd51ab494d559ba9374e4fea61a2d4fbffa3d3727da6c5026dd8808a21.js/assets/frontend/govuk_publishing_c... https://www.gov.uk/assets/frontend/govuk_publishing_components/load-analytics-7796c7fd51ab494d559ba9374e4fea61a2d4fbffa3d3727da6c5026dd8808a21.js — 200 — 12.0 KiB — 10 ms — h2https://www.gov.uk/assets/frontend/application-b88472b775464b326384095c50fa92796f127fa6dffff4f6ad48aca27abc1145.css/assets/frontend/application-b88472... https://www.gov.uk/assets/frontend/application-b88472b775464b326384095c50fa92796f127fa6dffff4f6ad48aca27abc1145.css — 200 — 36.8 KiB — 13 ms — h2https://www.gov.uk/assets/frontend/application-760b7ab26c68ec64b1ac8d1645828bf46aef2dec8a9f0611ca03aaca505e53ba.js/assets/frontend/application-760b7a... https://www.gov.uk/assets/frontend/application-760b7ab26c68ec64b1ac8d1645828bf46aef2dec8a9f0611ca03aaca505e53ba.js — 200 — 41.0 KiB — 13 ms — h2https://www.gov.uk/assets/frontend/govuk_publishing_components/icon-close-eecb5fdf67d1688ddf2f93e6e09d5f87b9b24e0fc53596ad2a65cf187c2c7c76.svg/assets/frontend/govuk_publishing_c... https://www.gov.uk/assets/frontend/govuk_publishing_components/icon-close-eecb5fdf67d1688ddf2f93e6e09d5f87b9b24e0fc53596ad2a65cf187c2c7c76.svg — 200 — 514 B — 4 ms — h3https://www.gov.uk/assets/frontend/govuk-crest-9f82a3631d8ac5feb4660345a2b44ca98f077b48248f2cc139a0f412355bebef.svg/assets/frontend/govuk-crest-9f82a3... https://www.gov.uk/assets/frontend/govuk-crest-9f82a3631d8ac5feb4660345a2b44ca98f077b48248f2cc139a0f412355bebef.svg — 200 — 14.6 KiB — 4 ms — h3https://www.gov.uk/assets/frontend/bold-b542beb274-v2-35bf540bb39615b6a517986f3aa83f7fefa1efd1878603eeeb196488078542d1.woff2/assets/frontend/bold-b542beb274-v2... https://www.gov.uk/assets/frontend/bold-b542beb274-v2-35bf540bb39615b6a517986f3aa83f7fefa1efd1878603eeeb196488078542d1.woff2 — 200 — 31.1 KiB — 10 ms — h3https://www.gov.uk/assets/frontend/light-94a07e06a1-v2-01565b0034e61d4609689bbb7ae0be844701f3812c8fe029fa1659b7ef3aa94f.woff2/assets/frontend/light-94a07e06a1-v... https://www.gov.uk/assets/frontend/light-94a07e06a1-v2-01565b0034e61d4609689bbb7ae0be844701f3812c8fe029fa1659b7ef3aa94f.woff2 — 200 — 33.0 KiB — 9 ms — h3https://www.gov.uk/assets/frontend/homepage/travel-advice-blue-icon-featured-a03f6981ba9d86e6b84ecfe7bb28557dad14cf00b5270082cd3d3e264e6e63e0.png/assets/frontend/homepage/travel-ad... https://www.gov.uk/assets/frontend/homepage/travel-advice-blue-icon-featured-a03f6981ba9d86e6b84ecfe7bb28557dad14cf00b5270082cd3d3e264e6e63e0.png — 200 — 1.1 KiB — 11 ms — h3https://www.gov.uk/assets/frontend/homepage/photo-id-featured-9e48313e57cbf07cdcc1e3773dacf538c0489be9b54d6cb43ff0cad41076e22b.png/assets/frontend/homepage/photo-id-... https://www.gov.uk/assets/frontend/homepage/photo-id-featured-9e48313e57cbf07cdcc1e3773dacf538c0489be9b54d6cb43ff0cad41076e22b.png — 200 — 1.6 KiB — 10 ms — h3https://www.gov.uk/assets/frontend/homepage/find-a-job-4d38717b0451da3bb223ddea7f681d79e48c1c022da5a08f16aba3f681503150.png/assets/frontend/homepage/find-a-jo... https://www.gov.uk/assets/frontend/homepage/find-a-job-4d38717b0451da3bb223ddea7f681d79e48c1c022da5a08f16aba3f681503150.png — 200 — 1.7 KiB — 10 ms — h3https://www.gov.uk/assets/frontend/app-promo/govuk-app-icon-0bca94cf05737106d8e80f32a66f773d7b6ff9b9652fc555917d855914309af0.png/assets/frontend/app-promo/govuk-ap... https://www.gov.uk/assets/frontend/app-promo/govuk-app-icon-0bca94cf05737106d8e80f32a66f773d7b6ff9b9652fc555917d855914309af0.png — 200 — 4.6 KiB — 10 ms — h3https://www.gov.uk/assets/frontend/favicon-d962d21b5bb443f546c097ea21b567cde639adef7370da45be5e349ba8d62d33.svg/assets/frontend/favicon-d962d21b5b... https://www.gov.uk/assets/frontend/favicon-d962d21b5bb443f546c097ea21b567cde639adef7370da45be5e349ba8d62d33.svg — 200 — 1.2 KiB — 2 ms — h3
HTML JavaScript CSS Images Fonts XHR/Fetch Other
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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