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https://gamblingcommission.gov.uk

Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
90
GRADE
A
FIX
2
REVIEW
2
PASS
11
INFO
2

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

Mobile Desktop
64
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.

5.34 s

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

6.36 s

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.

5.34 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.

6.36 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
11 PASS 2 REVIEW 2 FIX
D
Third-Party Impact
Action
100% third-party, 0 ms blocking
FIX
100% third-party, 0 ms blocking
Warning::
Third-party code accounts for 100% of page weight (803.7 KiB of 803.9 KiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
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.

C
Image Optimization
Action
7 images, 0 KB saveable
REVIEW
7 images, 0 KB saveable
Warning::
https://images.ctfassets.net/j16ev64qyf6l/2jMEUcwo... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://images.ctfassets.net/j16ev64qyf6l/2T4vdexw... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://images.ctfassets.net/j16ev64qyf6l/6BhmAA8n... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://images.ctfassets.net/j16ev64qyf6l/6EhW9Fs3... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://images.ctfassets.net/j16ev64qyf6l/28vB0ILL... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://images.ctfassets.net/j16ev64qyf6l/2ntAXPE2... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://images.ctfassets.net/j16ev64qyf6l/5GTaAzXJ... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
7 images 385 KB
0 oversized -0 KB
7 legacy format
7 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

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

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
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A
Page Weight Budget
804 KB transferred, 30 requests
PASS
804 KB transferred, 30 requests
Info::
Page weighs 1.4 MB (804 KB transferred)
Info::
30 HTTP requests
Info::
Estimated 0.16 g CO2 per page load
804 KB / 2.4 MB budget
804 KB transferred
30 requests
0.16 g CO2 per page load
Images 385.5 KiB 48%
Other 136.4 KiB 17%
CSS 107.7 KiB 13%
JavaScript 84.4 KiB 11%
Fonts 70.6 KiB 9%
HTML 18.2 KiB 2%
Other 1.1 KiB 0%
0 2.4 MB 4.9 MB
Under budget
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
314ms total JS execution
PASS
314ms total JS execution
Info::
Unattributable: 161ms CPU time
Info::
https://www.gamblingcommission.gov.uk/: 154ms CPU time
Warning::
Third-party scripts: 314ms (100% of total)

Main Thread Breakdown

Other 46% Style & Layout 24% Script Evaluation 13% Parse HTML & CSS 10% Script Parsing & Compilation 4% Rendering 3%
ScriptTotalScriptingParse/CompileParty
Unattributable161ms4ms0ms3rd
https://www.gamblingcommission.gov.uk/154ms3ms0ms3rd
A+
Font Loading
2 fonts (71 KB)
PASS
2 fonts (71 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

71 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 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s FCP 5.3 s LCP 6.4 shttps://fonts.gstatic.com/s/nunito/v32/XRXV3I6Li01BKofINeaBTMnFcQ.woff2XRXV3I6Li01BKofINeaBTMn... https://fonts.gstatic.com/s/nunito/v32/XRXV3I6Li01BKofINeaBTMnFcQ.woff2 — 38.3 KiB — 53 ms — font-display: swaphttps://fonts.gstatic.com/s/spartan/v22/l7gfbjR61M69yt8Z2QKtlAXJExs.woff2l7gfbjR61M69yt8Z2QKtlAX... https://fonts.gstatic.com/s/spartan/v22/l7gfbjR61M69yt8Z2QKtlAXJExs.woff2 — 32.3 KiB — 51 ms — font-display: swap
XRXV3I6Li01BKofINeaBTMn... woff2 swap
Size 38 KB
Load time 53 ms
Start 466 ms
Risk FOUT — text flashes from fallback to web font
l7gfbjR61M69yt8Z2QKtlAX... woff2 swap
Size 32 KB
Load time 51 ms
Start 467 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
8 scripts, 22 KB unused
PASS
8 scripts, 22 KB unused
Warning::
https://code.jquery.com/jquery-3.6.0.min.js: 22 KB unused (73%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.gamblingcommission.gov.uk/public/javas...: unminified — 12 KB could be saved
Info::
Total unused JavaScript: 22 KB
22 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://code.jquery.com/jquery-3.6.0.min.js31 KB22 KB (73%)✓3rd
https://www.gamblingcommission.gov.uk/public/javascripts/active-nav.js1 KB—✓3rd
https://www.gamblingcommission.gov.uk/public/javascripts/grecaptchax.js1 KB—✓3rd
https://www.gamblingcommission.gov.uk/public/search/js/search.min.js17 KB—✓3rd
https://www.gamblingcommission.gov.uk/public/javascripts/gov.js27 KB—✗3rd
https://www.gamblingcommission.gov.uk/public/javascripts/all.js3 KB—✓3rd
https://www.gamblingcommission.gov.uk/public/javascripts/timeline.js1 KB—✓3rd
https://www.gamblingcommission.gov.uk/public/javascripts/inline.js4 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

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
30 resources · 804 KB · 22 KB savings available
PASS
30 resources · 804 KB · 22 KB savings available
Info::
Within 1MB page-weight target
Got: 804 KB
Warning::
29 third-party resources (100% of weight)
30 resources · 803.9 KiB · 29 third-party Within 1MB page-weight target
Image 65% · 521.7 KiB
CSS 13% · 107.7 KiB
JavaScript 11% · 84.4 KiB
Font 9% · 70.6 KiB
Document 2% · 18.4 KiB
Other 0% · 1.1 KiB

~22.1 KiB of savings available

Remove unused JavaScript: 22.1 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
Network Waterfall
30 requests over 742ms
INFO
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s FCP 5.3 s LCP 6.4 shttps://gamblingcommission.gov.uk// https://gamblingcommission.gov.uk/ — 301 — 239 B — 80 ms — http/1.1https://www.gamblingcommission.gov.uk/www.gamblingcommission.gov.uk/ https://www.gamblingcommission.gov.uk/ — 200 — 18.2 KiB — 114 ms — http/1.1https://www.gamblingcommission.gov.uk/public/stylesheets/cdnapplication.csswww.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/stylesheets/cdnapplication.css — 200 — 37.9 KiB — 60 ms — http/1.1https://www.gamblingcommission.gov.uk/public/stylesheets/application.csswww.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/stylesheets/application.css — 200 — 38.1 KiB — 110 ms — http/1.1https://www.gamblingcommission.gov.uk/public/font-awesome/css/all.csswww.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/font-awesome/css/all.css — 200 — 16.8 KiB — 118 ms — http/1.1https://www.gamblingcommission.gov.uk/public/stylesheets/styles.css?v=3www.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/stylesheets/styles.css?v=3 — 200 — 11.9 KiB — 100 ms — http/1.1https://www.gamblingcommission.gov.uk/public/stylesheets/gcweb5.csswww.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/stylesheets/gcweb5.css — 200 — 1.2 KiB — 90 ms — http/1.1https://code.jquery.com/jquery-3.6.0.min.jscode.jquery.com/jquery-3.6.0.min.js https://code.jquery.com/jquery-3.6.0.min.js — 200 — 30.5 KiB — 39 ms — h2https://images.ctfassets.net/j16ev64qyf6l/2ntAXPE2PlYnt3FGJpuVtf/ba119b1b32ddb454e30eb20132ef62a2/Gambling_Commission_logo.png?w=220images.ctfassets.net/j16ev64qyf6l/2... https://images.ctfassets.net/j16ev64qyf6l/2ntAXPE2PlYnt3FGJpuVtf/ba119b1b32ddb454e30eb20132ef62a2/Gambling_Commission_logo.png?w=220 — 200 — 7.9 KiB — 83 ms — h2https://images.ctfassets.net/j16ev64qyf6l/5GTaAzXJgGYUjkTg12XJ3P/674c17ad0c2b49169a90d1f765760860/reels.jpg?h=400images.ctfassets.net/j16ev64qyf6l/5... https://images.ctfassets.net/j16ev64qyf6l/5GTaAzXJgGYUjkTg12XJ3P/674c17ad0c2b49169a90d1f765760860/reels.jpg?h=400 — 200 — 46.7 KiB — 394 ms — h2https://fonts.googleapis.com/css?family=Oxygen:400,700&display=swapfonts.googleapis.com/css?family=Oxy... https://fonts.googleapis.com/css?family=Oxygen:400,700&display=swap — 200 — 901 B — 93 ms — h2https://images.ctfassets.net/j16ev64qyf6l/2jMEUcwohaEYZeydMsXPx1/41af0a6e548140926d1f93cf014a3cb0/safe.jpg?h=400images.ctfassets.net/j16ev64qyf6l/2... https://images.ctfassets.net/j16ev64qyf6l/2jMEUcwohaEYZeydMsXPx1/41af0a6e548140926d1f93cf014a3cb0/safe.jpg?h=400 — 200 — 31.4 KiB — 329 ms — h2https://fonts.googleapis.com/css2?family=Nunito:wght@400;500;600;700&family=Spartan:wght@400;600;700&display=swap&family=PT+Sans:wght@400;700&display=swapfonts.googleapis.com/css2?family=Nu... https://fonts.googleapis.com/css2?family=Nunito:wght@400;500;600;700&family=Spartan:wght@400;600;700&display=swap&family=PT+Sans:wght@400;700&display=swap — 200 — 973 B — 44 ms — h2https://images.ctfassets.net/j16ev64qyf6l/2T4vdexwuKX09KL8M6iTGU/4c0ae70acea170e2898f6c9ca778c957/fete2.jpeg?h=400images.ctfassets.net/j16ev64qyf6l/2... https://images.ctfassets.net/j16ev64qyf6l/2T4vdexwuKX09KL8M6iTGU/4c0ae70acea170e2898f6c9ca778c957/fete2.jpeg?h=400 — 200 — 112.0 KiB — 50 ms — h2https://images.ctfassets.net/j16ev64qyf6l/6BhmAA8nsnOT78ippC8WCy/fd9fb7b22b3bf1a3262677b0d0a8c449/logo-gamcare-desktop_426dfb1d.svgimages.ctfassets.net/j16ev64qyf6l/6... https://images.ctfassets.net/j16ev64qyf6l/6BhmAA8nsnOT78ippC8WCy/fd9fb7b22b3bf1a3262677b0d0a8c449/logo-gamcare-desktop_426dfb1d.svg — 200 — 1.9 KiB — 169 ms — h2https://www.gamblingcommission.gov.uk/public/javascripts/active-nav.jswww.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/javascripts/active-nav.js — 200 — 783 B — 35 ms — http/1.1https://www.gamblingcommission.gov.uk/public/javascripts/grecaptchax.jswww.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/javascripts/grecaptchax.js — 200 — 1.1 KiB — 36 ms — http/1.1https://www.gamblingcommission.gov.uk/public/search/js/search.min.jswww.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/search/js/search.min.js — 200 — 16.6 KiB — 43 ms — http/1.1https://www.gamblingcommission.gov.uk/public/javascripts/gov.jswww.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/javascripts/gov.js — 200 — 27.0 KiB — 65 ms — http/1.1https://www.gamblingcommission.gov.uk/public/javascripts/all.jswww.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/javascripts/all.js — 200 — 2.7 KiB — 38 ms — http/1.1https://www.gamblingcommission.gov.uk/public/javascripts/timeline.jswww.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/javascripts/timeline.js — 200 — 1.4 KiB — 68 ms — http/1.1https://images.ctfassets.net/j16ev64qyf6l/6EhW9Fs3LXtv2yGwzs8RD6/2f032dec7c0ac3ef49b5d90e8419adc0/Illegal_gambling_update_on_trends_and_data_approach__1_.pngimages.ctfassets.net/j16ev64qyf6l/6... https://images.ctfassets.net/j16ev64qyf6l/6EhW9Fs3LXtv2yGwzs8RD6/2f032dec7c0ac3ef49b5d90e8419adc0/Illegal_gambling_update_on_trends_and_data_approach__1_.png — 200 — 161.7 KiB — 71 ms — h2https://images.ctfassets.net/j16ev64qyf6l/28vB0ILLOz6yxww1C6OVYH/9d8a484672e9aa318ca45013979e1498/Financial_risk_assessments_pilot_%C3%A2___update_on_post-pilot_analysis_1.pngimages.ctfassets.net/j16ev64qyf6l/2... https://images.ctfassets.net/j16ev64qyf6l/28vB0ILLOz6yxww1C6OVYH/9d8a484672e9aa318ca45013979e1498/Financial_risk_assessments_pilot_%C3%A2___update_on_post-pilot_analysis_1.png — 200 — 23.8 KiB — 73 ms — h2https://www.gamblingcommission.gov.uk/public/javascripts/inline.jswww.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/javascripts/inline.js — 200 — 4.4 KiB — 37 ms — http/1.1https://www.gamblingcommission.gov.uk/public/manifest.webmanifestwww.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/manifest.webmanifest — 200 — 1.1 KiB — 84 ms — http/1.1https://fonts.gstatic.com/s/nunito/v32/XRXV3I6Li01BKofINeaBTMnFcQ.woff2fonts.gstatic.com/s/nunito/v32/XRXV... https://fonts.gstatic.com/s/nunito/v32/XRXV3I6Li01BKofINeaBTMnFcQ.woff2 — 200 — 38.3 KiB — 53 ms — h3https://fonts.gstatic.com/s/spartan/v22/l7gfbjR61M69yt8Z2QKtlAXJExs.woff2fonts.gstatic.com/s/spartan/v22/l7g... https://fonts.gstatic.com/s/spartan/v22/l7gfbjR61M69yt8Z2QKtlAXJExs.woff2 — 200 — 32.3 KiB — 51 ms — h3https://www.gamblingcommission.gov.uk/public/images/icons/logo-grey.pngwww.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/images/icons/logo-grey.png — 200 — 126.5 KiB — 68 ms — http/1.1https://www.gamblingcommission.gov.uk/public/images/icons/android-icon-192x192.pngwww.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/images/icons/android-icon-192x192.png — 200 — 8.0 KiB — 37 ms — http/1.1https://www.gamblingcommission.gov.uk/public/images/icons/favicon-32x32.pngwww.gamblingcommission.gov.uk/publi... https://www.gamblingcommission.gov.uk/public/images/icons/favicon-32x32.png — 200 — 1.7 KiB — 44 ms — http/1.1
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
100% of JavaScript execution is third-party
First-party Third-party 314ms · 18KB · £3/mo
Unattributable
Other
Optional
Execution 161ms
Transfer 0 KB
Monthly Cost £2/mo
www.gamblingcommission.gov.uk
Other
Optional
Execution 154ms
Transfer 18 KB
Monthly Cost £2/mo

100% 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

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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