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Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
70
GRADE
C
FIX
6
REVIEW
1
PASS
8
INFO
2

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

Mobile Desktop
28
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.
77
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.

6.78 s

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

24.38 s

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

2.36 s

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

0.043

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

8.49 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.

24.38 s

Page Load Progression

406 ms
813 ms
1.2 s
1.6 s
2.0 s
2.4 s
2.8 s
3.2 s
Checks
17
8 PASS 1 REVIEW 6 FIX
F
Page Weight Budget
Action
4.0 MB transferred, 60 requests
FIX
4.0 MB transferred, 60 requests
Critical::
Page weighs 5.9 MB (4.0 MB transferred)
Info::
Fonts are 1.8 MB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 1.8 MB
Warning::
JavaScript is 1.1 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.1 MB
Info::
60 HTTP requests
Info::
Estimated 0.84 g CO2 per page load
4.0 MB / 2.4 MB budget
4.0 MB transferred
60 requests
0.84 g CO2 per page load
Fonts 1.8 MiB 45%
JavaScript 1.1 MiB 27%
Images 528.4 KiB 13%
Other 312.2 KiB 8%
CSS 197.5 KiB 5%
HTML 88.0 KiB 2%
Other 11.5 KiB 0%
Other 1004 B 0%
Other 44 B 0%
Other 21 B 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Over budget

Subset fonts to include only used characters, or switch to system font stacks.

Why this matters

Font payload is large — subset to used glyphs only, or fall back to system fonts (zero load time).

Source: web.dev font loading

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
100% third-party, 0 ms blocking
FIX
100% third-party, 0 ms blocking
Warning::
Third-party code accounts for 100% of page weight (4.0 MiB of 4.0 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
F
JS Execution Cost
Action
7367ms total JS execution
FIX
7367ms total JS execution
Warning::
https://www.bristol.ac.uk/: 2553ms CPU time
Warning::
Unattributable: 1675ms CPU time
Warning::
https://eu.gw.fortiabp.forticloud.com/api/v1/gw/st...: 848ms CPU time
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-MWC...: 830ms CPU time
Warning::
https://app.termly.io/resource-blocker/f00d1986-fa...: 593ms CPU time
Warning::
Third-party scripts: 7367ms (100% of total)

Main Thread Breakdown

Script Evaluation 43% Style & Layout 21% Other 21% Rendering 7% Script Parsing & Compilation 5%
ScriptTotalScriptingParse/CompileParty
https://www.bristol.ac.uk/2553ms38ms4ms3rd
Unattributable1675ms799ms0ms3rd
https://eu.gw.fortiabp.forticloud.com/api/v1/gw/static/js/vendor.www_bristol_ac_uk.hHsrG.v1768494982.js848ms557ms2ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-MWCJ929830ms667ms117ms3rd
https://app.termly.io/resource-blocker/f00d1986-fa46-46cf-a165-30f04408b1ce?autoBlock=on593ms459ms83ms3rd
https://www.bristol.ac.uk/assets/homepage-search/1.0.4/js/app.12148122.js280ms263ms15ms3rd
https://app.termly.io/resource-blocker/f00d1986-fa46-46cf-a165-30f04408b1ce202ms128ms73ms3rd
https://www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-480a6038.24fe62bd.js141ms102ms23ms3rd
https://www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-vendors.a3cb5fa7.js116ms56ms25ms3rd
https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-main-2.7.0.js71ms35ms3ms3rd

Showing top 10 of 11 scripts

F
JS Bundles
Action
35 scripts, 714 KB unused
FIX
35 scripts, 714 KB unused
Warning::
https://eu.gw.fortiabp.forticloud.com/api/v1/gw/st...: 141 KB unused (48%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.bristol.ac.uk/assets/homepage-search/1...: 94 KB unused (69%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.bristol.ac.uk/assets/homepage-search/1...: 94 KB unused (69%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://app.termly.io/resource-blocker/f00d1986-fa...: 83 KB unused (58%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.bristol.ac.uk/assets/responsive-web-pr...: 71 KB unused (94%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 714 KB
714 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://eu.gw.fortiabp.forticloud.com/api/v1/gw/static/js/main.www_bristol_ac_uk.hHsrG.v1768494982.js295 KB141 KB (48%)✓3rd
https://www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-480a6038.24fe62bd.js0 KB94 KB (69%)✓3rd
https://www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-480a6038.24fe62bd.js137 KB94 KB (69%)✓3rd
https://app.termly.io/resource-blocker/f00d1986-fa46-46cf-a165-30f04408b1ce144 KB83 KB (58%)✓3rd
https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-slider-2.7.0.js76 KB71 KB (94%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-MWCJ929195 KB57 KB (29%)✓3rd
https://app.termly.io/resource-blocker/f00d1986-fa46-46cf-a165-30f04408b1ce?autoBlock=on144 KB53 KB (37%)✓3rd
https://www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-vendors.a3cb5fa7.js124 KB46 KB (38%)✓3rd
https://eu.gw.fortiabp.forticloud.com/api/v1/gw/static/js/vendor.www_bristol_ac_uk.hHsrG.v1768494982.js75 KB43 KB (57%)✓3rd
https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-vimeo-2.7.0.js39 KB30 KB (78%)✓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

F
Page Weight Inventory
Action
60 resources · 4.0 MB · 714 KB savings available
FIX
60 resources · 4.0 MB · 714 KB savings available
Warning::
Page weight 3.0 MB over 1MB target
Got: 4.0 MB Expected: ≤ 1 MB
Info::
~714 KB of savings available
Warning::
59 third-party resources (100% of weight)
Info::
4 resources over 200KB
60 resources · 4.0 MiB · 59 third-party 3.0 MiB over 1MB target
Font 45% · 1.8 MiB
JavaScript 35% · 1.4 MiB
Image 13% · 543.5 KiB
CSS 5% · 197.5 KiB
Document 2% · 88.0 KiB
Other 0% · 12.7 KiB

~713.7 KiB of savings available

Remove unused JavaScript: 713.7 KiB
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
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

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
Image Optimization
3 images, 0 KB saveable
PASS
3 images, 0 KB saveable
Info::
All images are well-optimized
3 images 528 KB
0 oversized -0 KB
2 legacy format
0 missing dimensions CLS risk
A+
Font Loading
4 fonts (1853 KB)
PASS
4 fonts (1853 KB)
Info::
4 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

4

1853 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 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s 14.0 s 16.0 s 18.0 s 20.0 s 22.0 s 24.0 s FCP 6.8 s LCP 24.4 shttps://fonts.gstatic.com/s/opensans/v44/memvYaGs126MiZpBA-UvWbX2vVnXBbObj2OVTS-mu0SC55I.woff2memvYaGs126MiZpBA-UvWbX... https://fonts.gstatic.com/s/opensans/v44/memvYaGs126MiZpBA-UvWbX2vVnXBbObj2OVTS-mu0SC55I.woff2 — 42.0 KiB — 20 ms — font-display: swaphttps://fonts.gstatic.com/s/materialsymbolsrounded/v330/sykO-zNym6YjUruM-QrEh7-nyTnjDwKNJ_190FjpZIvLgyidOK7BDB_Qb9vUdV6_gjDK-P1Ju0XXkRzDgw.woff2sykO-zNym6YjUruM-QrEh7-... https://fonts.gstatic.com/s/materialsymbolsrounded/v330/sykO-zNym6YjUruM-QrEh7-nyTnjDwKNJ_190FjpZIvLgyidOK7BDB_Qb9vUdV6_gjDK-P1Ju0XXkRzDgw.woff2 — 1.4 MiB — 126 ms — font-display: swaphttps://fonts.gstatic.com/s/opensans/v44/memQYaGs126MiZpBA-UFUIcVXSCEkx2cmqvXlWq8tWZ0Pw86hd0Rk8ZkWVAewIMSdjE.woff2memQYaGs126MiZpBA-UFUIc... https://fonts.gstatic.com/s/opensans/v44/memQYaGs126MiZpBA-UFUIcVXSCEkx2cmqvXlWq8tWZ0Pw86hd0Rk8ZkWVAewIMSdjE.woff2 — 13.8 KiB — 33 ms — font-display: swaphttps://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/fonts/inter/Inter.woff2Inter.woff2 https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/fonts/inter/Inter.woff2 — 337.8 KiB — 73 ms — font-display: swap
memvYaGs126MiZpBA-UvWbX... woff2 swap
Size 42 KB
Load time 20 ms
Start 2.0 s
Risk FOUT — text flashes from fallback to web font
sykO-zNym6YjUruM-QrEh7-... woff2 swap
Size 1459 KB
Load time 126 ms
Start 2.0 s
Risk FOUT — text flashes from fallback to web font
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
memQYaGs126MiZpBA-UFUIc... woff2 swap
Size 14 KB
Load time 33 ms
Start 2.0 s
Risk FOUT — text flashes from fallback to web font
Inter.woff2 woff2 swap
Size 338 KB
Load time 73 ms
Start 2.1 s
Risk FOUT — text flashes from fallback to web font
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
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 ~898 KB and ~1796 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+
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
60 requests over 4036ms
INFO
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 18.0 s 20.0 s 22.0 s 24.0 s FCP 6.8 s LCP 24.4 shttps://bristol.ac.uk// https://bristol.ac.uk/ — 301 — 130 B — 69 ms — http/1.0https://www.bristol.ac.uk/www.bristol.ac.uk/ https://www.bristol.ac.uk/ — 200 — 88.0 KiB — 1.6 s — http/1.1https://eu.gw.fortiabp.forticloud.com/api/v1/gw/static/js/index.www_bristol_ac_uk.hHsrG.v1768494982.jseu.gw.fortiabp.forticloud.com/api/v... https://eu.gw.fortiabp.forticloud.com/api/v1/gw/static/js/index.www_bristol_ac_uk.hHsrG.v1768494982.js — 200 — 2.1 KiB — 211 ms — h2https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/css/responsive-web-project-main-2.7.0.csswww.bristol.ac.uk/assets/responsive... https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/css/responsive-web-project-main-2.7.0.css — 200 — 146.4 KiB — 49 ms — http/1.1https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/css/responsive-web-project-fullwidth-2.7.0.csswww.bristol.ac.uk/assets/responsive... https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/css/responsive-web-project-fullwidth-2.7.0.css — 200 — 39.8 KiB — 90 ms — http/1.1https://app.termly.io/resource-blocker/f00d1986-fa46-46cf-a165-30f04408b1ce?autoBlock=onapp.termly.io/resource-blocker/f00d... https://app.termly.io/resource-blocker/f00d1986-fa46-46cf-a165-30f04408b1ce?autoBlock=on — 200 — 143.8 KiB — 215 ms — h3https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/css/responsive-web-project-homepage-2.7.0.csswww.bristol.ac.uk/assets/responsive... https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/css/responsive-web-project-homepage-2.7.0.css — 200 — 6.4 KiB — 89 ms — http/1.1https://www.bristol.ac.uk/media-library/sites/homepage/images/homepage-1.jpgwww.bristol.ac.uk/media-library/sit... https://www.bristol.ac.uk/media-library/sites/homepage/images/homepage-1.jpg — 200 — 516.3 KiB — 213 ms — http/1.1https://www.bristol.ac.uk/assets/homepage-search/1.0.4/css/app.565b7505.csswww.bristol.ac.uk/assets/homepage-s... https://www.bristol.ac.uk/assets/homepage-search/1.0.4/css/app.565b7505.css — 200 — 2.0 KiB — 76 ms — http/1.1https://www.bristol.ac.uk/assets/homepage-search/1.0.4/js/app.12148122.jswww.bristol.ac.uk/assets/homepage-s... https://www.bristol.ac.uk/assets/homepage-search/1.0.4/js/app.12148122.js — 200 — 9.8 KiB — 88 ms — http/1.1https://www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-vendors.a3cb5fa7.jswww.bristol.ac.uk/assets/homepage-s... https://www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-vendors.a3cb5fa7.js — 200 — 123.8 KiB — 94 ms — http/1.1https://fonts.googleapis.com/css2?family=Open+Sans:ital,wght@0,400;0,600;0,700;1,400&display=swapfonts.googleapis.com/css2?family=Op... https://fonts.googleapis.com/css2?family=Open+Sans:ital,wght@0,400;0,600;0,700;1,400&display=swap — 200 — 2.4 KiB — 24 ms — h2https://fonts.googleapis.com/css2?family=Material+Symbols+Rounded:opsz,wght,FILL,GRAD@48,100..700,0..1,0&display=swapfonts.googleapis.com/css2?family=Ma... https://fonts.googleapis.com/css2?family=Material+Symbols+Rounded:opsz,wght,FILL,GRAD@48,100..700,0..1,0&display=swap — 200 — 517 B — 26 ms — h2https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/favicons/site.webmanifestwww.bristol.ac.uk/assets/responsive... https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/favicons/site.webmanifest — 200 — 1004 B — 68 ms — http/1.1https://eu.gw.fortiabp.forticloud.com/api/v1/gw/static/js/main.www_bristol_ac_uk.hHsrG.v1768494982.jseu.gw.fortiabp.forticloud.com/api/v... https://eu.gw.fortiabp.forticloud.com/api/v1/gw/static/js/main.www_bristol_ac_uk.hHsrG.v1768494982.js — 200 — 295.3 KiB — 83 ms — h2https://eu.gw.fortiabp.forticloud.com/api/v1/gw/static/js/vendor.www_bristol_ac_uk.hHsrG.v1768494982.jseu.gw.fortiabp.forticloud.com/api/v... https://eu.gw.fortiabp.forticloud.com/api/v1/gw/static/js/vendor.www_bristol_ac_uk.hHsrG.v1768494982.js — 200 — 74.8 KiB — 99 ms — h2https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/images/logos/uob-logo.svgwww.bristol.ac.uk/assets/responsive... https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/images/logos/uob-logo.svg — 200 — 12.2 KiB — 38 ms — http/1.1https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-main-2.7.0.jswww.bristol.ac.uk/assets/responsive... https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-main-2.7.0.js — 200 — 14.2 KiB — 38 ms — http/1.1https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-slider-2.7.0.jswww.bristol.ac.uk/assets/responsive... https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-slider-2.7.0.js — 200 — 75.8 KiB — 55 ms — http/1.1https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-vimeo-2.7.0.jswww.bristol.ac.uk/assets/responsive... https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-vimeo-2.7.0.js — 200 — 38.8 KiB — 44 ms — http/1.1https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-youtube-2.7.0.jswww.bristol.ac.uk/assets/responsive... https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-youtube-2.7.0.js — 200 — 1.5 KiB — 36 ms — http/1.1https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-pagination-2.7.0.jswww.bristol.ac.uk/assets/responsive... https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-pagination-2.7.0.js — 200 — 1.6 KiB — 35 ms — http/1.1https://www.googletagmanager.com/gtm.js?id=GTM-MWCJ929www.googletagmanager.com/gtm.js?id=... 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INFO
100% of JavaScript execution is third-party
First-party Third-party 7367ms · 795KB · £76/mo
www.bristol.ac.uk
Other
Costly
Execution 2553ms
Transfer 88 KB
Monthly Cost £26/mo
Unattributable
Other
Costly
Execution 1675ms
Transfer 0 KB
Monthly Cost £17/mo
eu.gw.fortiabp.forticloud.com
Other
Costly
Execution 848ms
Transfer 75 KB
Unused 57%
Monthly Cost £9/mo
Google Tag Manager
Tag Manager
Costly
Execution 830ms
Transfer 195 KB
Unused 29%
Monthly Cost £9/mo
app.termly.io
Other
Costly
Execution 593ms
Transfer 144 KB
Unused 37%
Monthly Cost £6/mo
www.bristol.ac.uk
Other
Costly
Execution 280ms
Transfer 10 KB
Monthly Cost £3/mo
app.termly.io
Other
Costly
Execution 202ms
Transfer 144 KB
Unused 58%
Monthly Cost £2/mo
www.bristol.ac.uk
Other
Optional
Execution 141ms
Transfer 0 KB
Unused 69%
Monthly Cost £1/mo
www.bristol.ac.uk
Other
Optional
Execution 116ms
Transfer 124 KB
Unused 38%
Monthly Cost £1/mo
www.bristol.ac.uk
Other
Optional
Execution 71ms
Transfer 14 KB
Monthly Cost £1/mo
app.termly.io
Other
Optional
Execution 59ms
Transfer 2 KB
Monthly Cost £1/mo

These scripts may cost more than they're worth

  • www.bristol.ac.uk adds 2553ms and costs ~£26/month
  • Unattributable adds 1675ms and costs ~£17/month
  • eu.gw.fortiabp.forticloud.com adds 848ms and costs ~£9/month
  • Google Tag Manager adds 830ms and costs ~£9/month
  • app.termly.io adds 593ms and costs ~£6/month
  • www.bristol.ac.uk adds 280ms and costs ~£3/month
  • app.termly.io adds 202ms and costs ~£2/month

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

www.bristol.ac.uk takes 2553ms 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

Unattributable takes 1675ms 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

eu.gw.fortiabp.forticloud.com takes 848ms 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

57% of eu.gw.fortiabp.forticloud.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

Google Tag Manager takes 830ms 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

app.termly.io takes 593ms 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

www.bristol.ac.uk takes 280ms 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

app.termly.io takes 202ms 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

58% of app.termly.io'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

69% of www.bristol.ac.uk'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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