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https://publications.parliament.uk

Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
98
GRADE
A+
FIX
1
REVIEW
1
PASS
13
INFO
2

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

Mobile Desktop
98
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
83
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
69
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
91
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.

1.58 s

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

1.71 s

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

11 ms

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

0.065

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

2.53 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.

1.72 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
17
13 PASS 1 REVIEW 1 FIX
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.

B
Image Optimization
9 images, 0 KB saveable
REVIEW
9 images, 0 KB saveable
Info::
All images are well-optimized
9 images 41 KB
0 oversized -0 KB
9 legacy format
0 missing dimensions CLS risk
A+
Page Weight Budget
74 KB transferred, 18 requests
PASS
74 KB transferred, 18 requests
Info::
Page weighs 143 KB (74 KB transferred)
Info::
18 HTTP requests
Info::
Estimated 0.02 g CO2 per page load
74 KB / 2.4 MB budget
74 KB transferred
18 requests
0.02 g CO2 per page load
Images 41.4 KiB 56%
JavaScript 16.1 KiB 22%
CSS 11.2 KiB 15%
HTML 3.7 KiB 5%
Other 986 B 1%
Other 644 B 1%
0 2.4 MB 4.9 MB
Under budget
A+
Third-Party Impact
7% third-party, 0 ms blocking
PASS
7% third-party, 0 ms blocking
Info::
Third-party code accounts for 7% of page weight (5.5 KiB of 74.0 KiB)
Info::
Third-party blocking time is low (0 ms)
93%
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+
JS Execution Cost
439ms total JS execution
PASS
439ms total JS execution
Info::
https://publications.parliament.uk/cdn-cgi/challen...: 213ms CPU time
Info::
Unattributable: 113ms CPU time
Info::
https://publications.parliament.uk/: 113ms CPU time
Info::
Third-party scripts: 113ms (26% of total)

Main Thread Breakdown

Script Evaluation 55% Other 29% Style & Layout 10%
ScriptTotalScriptingParse/CompileParty
https://publications.parliament.uk/cdn-cgi/challenge-platform/scripts/jsd/main.js213ms204ms2ms1st
Unattributable113ms5ms0ms3rd
https://publications.parliament.uk/113ms33ms2ms1st
A+
Font Loading
No web fonts (system fonts)
PASS
No web fonts (system fonts)
Info::
No web fonts loaded — system fonts are fastest
No web fonts loaded — system fonts are optimal.
A+
JS Bundles
2 scripts, 0 KB unused
PASS
2 scripts, 0 KB unused
0 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://cookiemanager.parliament.uk/cookie-manager-v2.js4 KB—✓3rd
https://publications.parliament.uk/cdn-cgi/challenge-platform/h/b/scripts/jsd/0b8fb825cb67/main.js?12 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
18 resources · 74 KB · 0 KB savings available
PASS
18 resources · 74 KB · 0 KB savings available
Info::
Within 1MB page-weight target
Got: 74 KB
Info::
2 third-party resources (7% of weight)
18 resources · 74.0 KiB · 2 third-party Within 1MB page-weight target
Image 56% · 41.7 KiB
JavaScript 22% · 16.1 KiB
CSS 15% · 11.2 KiB
Document 5% · 3.7 KiB
Other 2% · 1.3 KiB
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: Cloudflare

Network Waterfall
18 requests over 494ms
INFO
0 ms 500 ms 1.0 s 1.5 s FCP 1.6 s LCP 1.7 shttps://publications.parliament.uk// https://publications.parliament.uk/ — 200 — 3.7 KiB — 189 ms — h2https://publications.parliament.uk/styles/global.css/styles/global.css https://publications.parliament.uk/styles/global.css — 200 — 7.0 KiB — 61 ms — h2https://cookiemanager.parliament.uk/cookie-manager-v2.csscookiemanager.parliament.uk/cookie-... https://cookiemanager.parliament.uk/cookie-manager-v2.css — 200 — 1.6 KiB — 104 ms — h3https://publications.parliament.uk/server-side/images/parliament_logo.gif/server-side/images/parliament_logo... https://publications.parliament.uk/server-side/images/parliament_logo.gif — 200 — 6.2 KiB — 57 ms — h2https://cookiemanager.parliament.uk/cookie-manager-v2.jscookiemanager.parliament.uk/cookie-... https://cookiemanager.parliament.uk/cookie-manager-v2.js — 200 — 4.0 KiB — 101 ms — h3https://publications.parliament.uk/pa/img/icon_about_parliament.jpg/pa/img/icon_about_parliament.jpg https://publications.parliament.uk/pa/img/icon_about_parliament.jpg — 200 — 7.0 KiB — 97 ms — h2https://publications.parliament.uk/pa/img/icon_members_and_staff.jpg/pa/img/icon_members_and_staff.jpg https://publications.parliament.uk/pa/img/icon_members_and_staff.jpg — 200 — 7.2 KiB — 83 ms — h2https://publications.parliament.uk/pa/img/icon_business.jpg/pa/img/icon_business.jpg https://publications.parliament.uk/pa/img/icon_business.jpg — 200 — 7.4 KiB — 92 ms — h2https://publications.parliament.uk/pa/img/icon_records_and_publications.jpg/pa/img/icon_records_and_publicatio... https://publications.parliament.uk/pa/img/icon_records_and_publications.jpg — 200 — 7.4 KiB — 70 ms — h2https://publications.parliament.uk/pa/img/icon_house_of_commons.png/pa/img/icon_house_of_commons.png https://publications.parliament.uk/pa/img/icon_house_of_commons.png — 200 — 2.1 KiB — 53 ms — h2https://publications.parliament.uk/pa/img/icon_house_of_lords.png/pa/img/icon_house_of_lords.png https://publications.parliament.uk/pa/img/icon_house_of_lords.png — 200 — 2.0 KiB — 68 ms — h2https://publications.parliament.uk/pa/img/icon_parliament_live.png/pa/img/icon_parliament_live.png https://publications.parliament.uk/pa/img/icon_parliament_live.png — 200 — 1.5 KiB — 81 ms — h2https://publications.parliament.uk/styles/global_print.css/styles/global_print.css https://publications.parliament.uk/styles/global_print.css — 200 — 2.7 KiB — 84 ms — h2https://publications.parliament.uk/images/global/topnavborder.gif/images/global/topnavborder.gif https://publications.parliament.uk/images/global/topnavborder.gif — 200 — 539 B — 53 ms — h2https://publications.parliament.uk/cdn-cgi/challenge-platform/scripts/jsd/main.js/cdn-cgi/challenge-platform/scripts... https://publications.parliament.uk/cdn-cgi/challenge-platform/scripts/jsd/main.js — 302 — 373 B — 20 ms — h2https://publications.parliament.uk/cdn-cgi/challenge-platform/h/b/scripts/jsd/0b8fb825cb67/main.js?/cdn-cgi/challenge-platform/h/b/scr... https://publications.parliament.uk/cdn-cgi/challenge-platform/h/b/scripts/jsd/0b8fb825cb67/main.js? — 200 — 12.1 KiB — 23 ms — h2https://publications.parliament.uk/cdn-cgi/challenge-platform/h/b/jsd/oneshot/0b8fb825cb67/0.3453082048108739:1776885207:s1-Xd2z2ZphUAQo4UnyCzJ5rgvpUx1zX3s_Dhqt1Wlw/9f07450c3f6fd124/cdn-cgi/challenge-platform/h/b/jsd... https://publications.parliament.uk/cdn-cgi/challenge-platform/h/b/jsd/oneshot/0b8fb825cb67/0.3453082048108739:1776885207:s1-Xd2z2ZphUAQo4UnyCzJ5rgvpUx1zX3s_Dhqt1Wlw/9f07450c3f6fd124 — 200 — 986 B — 26 ms — h2https://publications.parliament.uk/favicon.ico/favicon.ico https://publications.parliament.uk/favicon.ico — 200 — 271 B — 62 ms — h2
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
26% of JavaScript execution is third-party
First-party Third-party 113ms · 0KB · £1/mo
Unattributable
Other
Optional
Execution 113ms
Transfer 0 KB
Monthly Cost £1/mo

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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