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https://reading.ac.uk

Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
69
GRADE
D
FIX
5
REVIEW
2
PASS
6
INFO
2

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

Mobile Desktop
83
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
88
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.
92
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.

1.50 s

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

2.18 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.

0.026

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

1.50 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.

2.23 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
15
6 PASS 2 REVIEW 5 FIX
F
Page Weight Budget
Action
3.7 MB transferred, 64 requests
FIX
3.7 MB transferred, 64 requests
Warning::
Page weighs 5.5 MB (3.7 MB transferred)
Warning::
Images are 1.9 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 1.9 MB
Warning::
JavaScript is 1.2 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.2 MB
Info::
CSS is 286 KB — consider purging unused styles
Remove unused CSS rules with tools like PurgeCSS to reduce stylesheet size.
Got: 286 KB
Info::
64 HTTP requests
Info::
Estimated 0.77 g CO2 per page load
3.7 MB / 2.4 MB budget
3.7 MB transferred
64 requests
0.77 g CO2 per page load
Images 1.9 MiB 52%
JavaScript 1.2 MiB 32%
CSS 285.5 KiB 8%
Fonts 175.8 KiB 5%
HTML 128.5 KiB 3%
Other 10.7 KiB 0%
Other 1.9 KiB 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Over budget

Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.

Why this matters

Image bandwidth is high — modern formats (WebP/AVIF) and resizing typically cut it 50%+.

Source: web.dev

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

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 (3.7 MiB of 3.7 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
F
JS Bundles
Action
17 scripts, 621 KB unused
FIX
17 scripts, 621 KB unused
Warning::
https://www.reading.ac.uk/homepage/web/files/dr-ho...: 102 KB unused (58%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=AW-110...: 87 KB unused (61%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=DC-137...: 81 KB unused (61%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=DC-130...: 81 KB unused (62%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=DC-855...: 81 KB unused (62%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 621 KB
621 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.reading.ac.uk/homepage/web/files/dr-homepage/web-library.min.js177 KB102 KB (58%)✓3rd
https://www.googletagmanager.com/gtag/js?id=AW-11016496176&cx=c&gtm=4e64k0144 KB87 KB (61%)✓3rd
https://www.googletagmanager.com/gtag/js?id=DC-13730620&cx=c&gtm=4e64k0132 KB81 KB (61%)✓3rd
https://www.googletagmanager.com/gtag/js?id=DC-13024755&cx=c&gtm=4e64k0129 KB81 KB (62%)✓3rd
https://www.googletagmanager.com/gtag/js?id=DC-8556031&cx=c&gtm=4e64k0129 KB81 KB (62%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-TC325M192 KB80 KB (41%)✓3rd
https://www.reading.ac.uk/homepage/web/files/dr-homepage/js-jquery-2.1.1.js83 KB56 KB (68%)✓3rd
https://app.termly.io/resource-blocker/b846a047-fc56-4159-aaf3-7bdc36e97907143 KB54 KB (38%)✓3rd
https://www.reading.ac.uk/homepage/web/files/dr-homepage/js-slider2.js5 KB—✓3rd
https://www.reading.ac.uk/homepage/web/files/dr-homepage/web-components.min.js18 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

F
Page Weight Inventory
Action
64 resources · 3.7 MB · 621 KB savings available
FIX
64 resources · 3.7 MB · 621 KB savings available
Warning::
Page weight 2.7 MB over 1MB target
Got: 3.7 MB Expected: ≤ 1 MB
Info::
~621 KB of savings available
Warning::
63 third-party resources (100% of weight)
Info::
2 resources over 200KB
64 resources · 3.7 MiB · 63 third-party 2.7 MiB over 1MB target
Image 52% · 1.9 MiB
JavaScript 32% · 1.2 MiB
CSS 8% · 285.5 KiB
Font 5% · 175.8 KiB
Document 3% · 128.9 KiB
Other 0% · 10.7 KiB

~621.1 KiB of savings available

Remove unused JavaScript: 621.1 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
Image Optimization
Action
26 images, 0 KB saveable
REVIEW
26 images, 0 KB saveable
Warning::
https://www.reading.ac.uk/homepage/web/multimediaf... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.reading.ac.uk/homepage/web/multimediaf... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.reading.ac.uk/homepage/web/multimediaf... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.reading.ac.uk/homepage/web/multimediaf... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.reading.ac.uk/homepage/web/multimediaf... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.reading.ac.uk/homepage/web/multimediaf... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.reading.ac.uk/homepage/web/multimediaf... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.reading.ac.uk/homepage/web/multimediaf... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.reading.ac.uk/homepage/web/multimediaf... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.reading.ac.uk/homepage/web/multimediaf... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.reading.ac.uk/homepage/web/multimediaf... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.reading.ac.uk/homepage/web/multimediaf... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
26 images 1.9 MB
0 oversized -0 KB
26 legacy format
12 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

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+
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
444ms total JS execution
PASS
444ms total JS execution
Info::
https://www.reading.ac.uk/: 109ms CPU time
Info::
https://app.termly.io/resource-blocker/b846a047-fc...: 94ms CPU time
Info::
https://www.googletagmanager.com/gtm.js?id=GTM-TC3...: 90ms CPU time
Info::
Unattributable: 80ms CPU time
Info::
https://www.reading.ac.uk/homepage/web/files/dr-ho...: 70ms CPU time
Warning::
Third-party scripts: 444ms (100% of total)

Main Thread Breakdown

Script Evaluation 48% Style & Layout 18% Other 17% Script Parsing & Compilation 11%
ScriptTotalScriptingParse/CompileParty
https://www.reading.ac.uk/109ms1ms0ms3rd
https://app.termly.io/resource-blocker/b846a047-fc56-4159-aaf3-7bdc36e9790794ms70ms12ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-TC325M90ms73ms17ms3rd
Unattributable80ms2ms0ms3rd
https://www.reading.ac.uk/homepage/web/files/dr-homepage/web-library.min.js70ms44ms4ms3rd
A+
Font Loading
6 fonts (176 KB)
PASS
6 fonts (176 KB)
Info::
6 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

6

176 KB total

Render-blocking

0

of 6

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s 1.5 s 2.0 s FCP 1.5 s LCP 2.2 shttps://www.reading.ac.uk/homepage/web/files/campaigns/effra-light.woffeffra-light.woff https://www.reading.ac.uk/homepage/web/files/campaigns/effra-light.woff — 29.6 KiB — 72 ms — font-display: swaphttps://www.reading.ac.uk/homepage/web/files/campaigns/effra-medium.woffeffra-medium.woff https://www.reading.ac.uk/homepage/web/files/campaigns/effra-medium.woff — 28.8 KiB — 42 ms — font-display: swaphttps://www.reading.ac.uk/homepage/web/files/campaigns/effra-bold.woffeffra-bold.woff https://www.reading.ac.uk/homepage/web/files/campaigns/effra-bold.woff — 29.6 KiB — 50 ms — font-display: swaphttps://www.reading.ac.uk/homepage/web/files/campaigns/effra-regular.woffeffra-regular.woff https://www.reading.ac.uk/homepage/web/files/campaigns/effra-regular.woff — 30.3 KiB — 58 ms — font-display: swaphttps://www.reading.ac.uk/homepage/web/files/campaigns/rdgvesta-regular.woffrdgvesta-regular.woff https://www.reading.ac.uk/homepage/web/files/campaigns/rdgvesta-regular.woff — 28.7 KiB — 79 ms — font-display: swaphttps://www.reading.ac.uk/homepage/web/files/campaigns/effra-heavy.woffeffra-heavy.woff https://www.reading.ac.uk/homepage/web/files/campaigns/effra-heavy.woff — 28.9 KiB — 75 ms — font-display: swap
effra-light.woff woff swap
Size 30 KB
Load time 72 ms
Start 474 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
effra-medium.woff woff swap
Size 29 KB
Load time 42 ms
Start 538 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
effra-bold.woff woff swap
Size 30 KB
Load time 50 ms
Start 539 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
effra-regular.woff woff swap
Size 30 KB
Load time 58 ms
Start 539 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
rdgvesta-regular.woff woff swap
Size 29 KB
Load time 79 ms
Start 539 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
effra-heavy.woff woff swap
Size 29 KB
Load time 75 ms
Start 539 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 ~53 KB and ~106 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
Network Waterfall
64 requests over 1002ms
INFO
0 ms 500 ms 1.0 s 1.5 s 2.0 s FCP 1.5 s LCP 2.2 shttps://reading.ac.uk// https://reading.ac.uk/ — 301 — 384 B — 85 ms — http/1.1http://www.reading.ac.uk/www.reading.ac.uk/ http://www.reading.ac.uk/ — 307 — 0 B — 1 ms — http/1.1https://www.reading.ac.uk/www.reading.ac.uk/ https://www.reading.ac.uk/ — 200 — 128.5 KiB — 204 ms — http/1.1https://www.reading.ac.uk/sc93/js/uor.module.cookie-blocker.jswww.reading.ac.uk/sc93/js/uor.modul... https://www.reading.ac.uk/sc93/js/uor.module.cookie-blocker.js — 200 — 5.4 KiB — 134 ms — http/1.1https://app.termly.io/resource-blocker/b846a047-fc56-4159-aaf3-7bdc36e97907app.termly.io/resource-blocker/b846... https://app.termly.io/resource-blocker/b846a047-fc56-4159-aaf3-7bdc36e97907 — 200 — 143.4 KiB — 178 ms — h3https://www.reading.ac.uk/homepage/web/files/dr-homepage/assets-css-main.csswww.reading.ac.uk/homepage/web/file... https://www.reading.ac.uk/homepage/web/files/dr-homepage/assets-css-main.css — 200 — 198.7 KiB — 174 ms — http/1.1https://www.reading.ac.uk/homepage/web/files/dr-homepage/february-assets-css-main.csswww.reading.ac.uk/homepage/web/file... https://www.reading.ac.uk/homepage/web/files/dr-homepage/february-assets-css-main.css — 200 — 12.7 KiB — 120 ms — http/1.1https://www.reading.ac.uk/homepage/web/files/dr-homepage/css-main.csswww.reading.ac.uk/homepage/web/file... https://www.reading.ac.uk/homepage/web/files/dr-homepage/css-main.css — 200 — 53.1 KiB — 138 ms — http/1.1https://www.reading.ac.uk/homepage/web/files/dr-homepage/css-hero-slider-style-2.csswww.reading.ac.uk/homepage/web/file... https://www.reading.ac.uk/homepage/web/files/dr-homepage/css-hero-slider-style-2.css — 200 — 18.0 KiB — 111 ms — http/1.1https://www.reading.ac.uk/homepage/web/files/dr-homepage/clearing-2025.csswww.reading.ac.uk/homepage/web/file... https://www.reading.ac.uk/homepage/web/files/dr-homepage/clearing-2025.css — 200 — 2.0 KiB — 97 ms — http/1.1https://www.reading.ac.uk/homepage/web/files/dr-homepage/js-modernizr.custom.04512.jswww.reading.ac.uk/homepage/web/file... https://www.reading.ac.uk/homepage/web/files/dr-homepage/js-modernizr.custom.04512.js — 200 — 15.6 KiB — 128 ms — http/1.1https://www.reading.ac.uk/homepage/web/multimediafiles/legacy-hamburger.pngwww.reading.ac.uk/homepage/web/mult... https://www.reading.ac.uk/homepage/web/multimediafiles/legacy-hamburger.png — 200 — 1.5 KiB — 31 ms — http/1.1https://www.reading.ac.uk/homepage/web/multimediafiles/legacy-uor-home-mobile.pngwww.reading.ac.uk/homepage/web/mult... https://www.reading.ac.uk/homepage/web/multimediafiles/legacy-uor-home-mobile.png — 200 — 6.1 KiB — 34 ms — http/1.1https://www.reading.ac.uk/homepage/web/multimediafiles/legacy-uor-home.pngwww.reading.ac.uk/homepage/web/mult... https://www.reading.ac.uk/homepage/web/multimediafiles/legacy-uor-home.png — 200 — 5.4 KiB — 32 ms — http/1.1https://www.reading.ac.uk/homepage/web/multimediafiles/centenary-homepage-banner.jpgwww.reading.ac.uk/homepage/web/mult... https://www.reading.ac.uk/homepage/web/multimediafiles/centenary-homepage-banner.jpg — 200 — 126.1 KiB — 85 ms — http/1.1https://www.reading.ac.uk/homepage/web/files/dr-homepage/js-jquery-2.1.1.jswww.reading.ac.uk/homepage/web/file... https://www.reading.ac.uk/homepage/web/files/dr-homepage/js-jquery-2.1.1.js — 200 — 82.7 KiB — 59 ms — http/1.1https://www.reading.ac.uk/homepage/web/files/dr-homepage/js-main.min.jswww.reading.ac.uk/homepage/web/file... https://www.reading.ac.uk/homepage/web/files/dr-homepage/js-main.min.js — 200 — 962 B — 42 ms — http/1.1https://www.reading.ac.uk/homepage/web/files/dr-homepage/js-slider2.jswww.reading.ac.uk/homepage/web/file... https://www.reading.ac.uk/homepage/web/files/dr-homepage/js-slider2.js — 200 — 4.7 KiB — 42 ms — http/1.1https://www.reading.ac.uk/homepage/web/files/dr-homepage/web-library.min.jswww.reading.ac.uk/homepage/web/file... https://www.reading.ac.uk/homepage/web/files/dr-homepage/web-library.min.js — 200 — 176.7 KiB — 43 ms — http/1.1https://www.reading.ac.uk/homepage/web/files/dr-homepage/web-components.min.jswww.reading.ac.uk/homepage/web/file... https://www.reading.ac.uk/homepage/web/files/dr-homepage/web-components.min.js — 200 — 18.3 KiB — 42 ms — http/1.1https://www.reading.ac.uk/homepage/web/multimediafiles/ug-open-days-banner.jpgwww.reading.ac.uk/homepage/web/mult... https://www.reading.ac.uk/homepage/web/multimediafiles/ug-open-days-banner.jpg — 200 — 404.4 KiB — 92 ms — http/1.1https://www.reading.ac.uk/homepage/web/multimediafiles/B35381-Spring-Webinar-Graphics-banner.jpgwww.reading.ac.uk/homepage/web/mult... https://www.reading.ac.uk/homepage/web/multimediafiles/B35381-Spring-Webinar-Graphics-banner.jpg — 200 — 233.1 KiB — 119 ms — http/1.1https://www.reading.ac.uk/homepage/web/files/campaigns/effra-light.woffwww.reading.ac.uk/homepage/web/file... https://www.reading.ac.uk/homepage/web/files/campaigns/effra-light.woff — 200 — 29.6 KiB — 72 ms — http/1.1https://www.googletagmanager.com/gtm.js?id=GTM-TC325Mwww.googletagmanager.com/gtm.js?id=... https://www.googletagmanager.com/gtm.js?id=GTM-TC325M — 200 — 192.5 KiB — 163 ms — h2https://www.reading.ac.uk/homepage/web/multimediafiles/sunrise-from-space.jpgwww.reading.ac.uk/homepage/web/mult... https://www.reading.ac.uk/homepage/web/multimediafiles/sunrise-from-space.jpg — 200 — 197.2 KiB — 63 ms — http/1.1https://www.reading.ac.uk/homepage/web/multimediafiles/2026-centenary-merchandise-desktop.jpgwww.reading.ac.uk/homepage/web/mult... https://www.reading.ac.uk/homepage/web/multimediafiles/2026-centenary-merchandise-desktop.jpg — 200 — 170.2 KiB — 41 ms — http/1.1https://www.reading.ac.uk/homepage/web/multimediafiles/2026-centenary-merchandise-mobile.jpgwww.reading.ac.uk/homepage/web/mult... https://www.reading.ac.uk/homepage/web/multimediafiles/2026-centenary-merchandise-mobile.jpg — 200 — 184.8 KiB — 68 ms — http/1.1https://www.reading.ac.uk/homepage/web/multimediafiles/assets-img-structure-bg-tile-red.pngwww.reading.ac.uk/homepage/web/mult... https://www.reading.ac.uk/homepage/web/multimediafiles/assets-img-structure-bg-tile-red.png — 200 — 4.6 KiB — 86 ms — http/1.1https://www.reading.ac.uk/homepage/web/multimediafiles/maginfying-glass-grey.svgwww.reading.ac.uk/homepage/web/mult... https://www.reading.ac.uk/homepage/web/multimediafiles/maginfying-glass-grey.svg — 200 — 1.1 KiB — 88 ms — http/1.1https://www.reading.ac.uk/homepage/web/multimediafiles/assets-home-Great-course-selection-296x150.jpgwww.reading.ac.uk/homepage/web/mult... https://www.reading.ac.uk/homepage/web/multimediafiles/assets-home-Great-course-selection-296x150.jpg — 200 — 75.6 KiB — 90 ms — http/1.1
0 ms 500 ms 1.0 s 1.5 s 2.0 s FCP 1.5 s LCP 2.2 shttps://reading.ac.uk// https://reading.ac.uk/ — 301 — 384 B — 85 ms — http/1.1http://www.reading.ac.uk/www.reading.ac.uk/ http://www.reading.ac.uk/ — 307 — 0 B — 1 ms — http/1.1https://www.reading.ac.uk/www.reading.ac.uk/ https://www.reading.ac.uk/ — 200 — 128.5 KiB — 204 ms — http/1.1https://www.reading.ac.uk/sc93/js/uor.module.cookie-blocker.jswww.reading.ac.uk/sc93/js/uor.modul... https://www.reading.ac.uk/sc93/js/uor.module.cookie-blocker.js — 200 — 5.4 KiB — 134 ms — http/1.1https://app.termly.io/resource-blocker/b846a047-fc56-4159-aaf3-7bdc36e97907app.termly.io/resource-blocker/b846... https://app.termly.io/resource-blocker/b846a047-fc56-4159-aaf3-7bdc36e97907 — 200 — 143.4 KiB — 178 ms — h3https://www.reading.ac.uk/homepage/web/files/dr-homepage/assets-css-main.csswww.reading.ac.uk/homepage/web/file... https://www.reading.ac.uk/homepage/web/files/dr-homepage/assets-css-main.css — 200 — 198.7 KiB — 174 ms — 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http/1.1https://www.reading.ac.uk/homepage/web/files/campaigns/effra-light.woffwww.reading.ac.uk/homepage/web/file... https://www.reading.ac.uk/homepage/web/files/campaigns/effra-light.woff — 200 — 29.6 KiB — 72 ms — http/1.1https://www.googletagmanager.com/gtm.js?id=GTM-TC325Mwww.googletagmanager.com/gtm.js?id=... https://www.googletagmanager.com/gtm.js?id=GTM-TC325M — 200 — 192.5 KiB — 163 ms — h2https://www.reading.ac.uk/homepage/web/multimediafiles/sunrise-from-space.jpgwww.reading.ac.uk/homepage/web/mult... https://www.reading.ac.uk/homepage/web/multimediafiles/sunrise-from-space.jpg — 200 — 197.2 KiB — 63 ms — http/1.1https://www.reading.ac.uk/homepage/web/multimediafiles/2026-centenary-merchandise-desktop.jpgwww.reading.ac.uk/homepage/web/mult... https://www.reading.ac.uk/homepage/web/multimediafiles/2026-centenary-merchandise-desktop.jpg — 200 — 170.2 KiB — 41 ms — 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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
100% of JavaScript execution is third-party
First-party Third-party 444ms · 641KB · £5/mo
www.reading.ac.uk
Other
Optional
Execution 109ms
Transfer 128 KB
Monthly Cost £1/mo
app.termly.io
Other
Optional
Execution 94ms
Transfer 143 KB
Unused 38%
Monthly Cost £1/mo
Google Tag Manager
Tag Manager
Optional
Execution 90ms
Transfer 192 KB
Unused 41%
Monthly Cost £1/mo
Unattributable
Other
Optional
Execution 80ms
Transfer 0 KB
Monthly Cost £1/mo
www.reading.ac.uk
Other
Optional
Execution 70ms
Transfer 177 KB
Unused 58%
Monthly Cost £1/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

58% of www.reading.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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