Performance
· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.Performance-focused optimization plan with CWV assessment, top offenders, and time estimates
First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.
2.11 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
8.79 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
570 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.057
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
4.55 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.
9.79 s
Page Load Progression
DThird-Party ImpactAction100% third-party, 0 ms blockingFIX
DJS Execution CostAction3175ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.birmingham.ac.uk/_s1t51Q_e03e1021-8a96-4a74-83eb-b7ac597b2ec5/static/modern/js/vendor.db9cf7f985c05a7d824f.mjs | 1107ms | 695ms | 7ms | 3rd |
| Unattributable | 885ms | 236ms | 0ms | 3rd |
| https://www.birmingham.ac.uk/ | 525ms | 19ms | 20ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-MM4Z3Q | 465ms | 374ms | 73ms | 3rd |
| https://cc.cdn.civiccomputing.com/9/cookieControl-9.x.min.js | 194ms | 156ms | 37ms | 3rd |
DJS BundlesAction20 scripts, 412 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.birmingham.ac.uk/_s1t51Q_e03e1021-8a96-4a74-83eb-b7ac597b2ec5/static/modern/js/vendor.db9cf7f985c05a7d824f.mjs | 399 KB | 208 KB (52%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-MM4Z3Q | 200 KB | 64 KB (32%) | ✓ | 3rd |
| https://www.birmingham.ac.uk/_s1t51Q_e03e1021-8a96-4a74-83eb-b7ac597b2ec5/static/modern/js/1443.a781644dc0ed3f47e50a.mjs | 125 KB | 59 KB (48%) | ✓ | 3rd |
| https://cc.cdn.civiccomputing.com/9/cookieControl-9.x.min.js | 123 KB | 58 KB (47%) | ✓ | 3rd |
| https://www.birmingham.ac.uk/_s1t51Q_e03e1021-8a96-4a74-83eb-b7ac597b2ec5/static/modern/js/app.767925685fd9a88fbd61.mjs | 62 KB | 23 KB (37%) | ✓ | 3rd |
| https://www.birmingham.ac.uk/_s1t51Q_e03e1021-8a96-4a74-83eb-b7ac597b2ec5/static/modern/js/features-courseSearch-courseSearch.f5e0f0bc2c5e1d28fdc1.mjs | 2 KB | — | ✓ | 3rd |
| https://www.birmingham.ac.uk/_s1t51Q_e03e1021-8a96-4a74-83eb-b7ac597b2ec5/static/modern/js/features-featuredVideoCards-featuredVideoCards.b9eb621a12669304f62f.mjs | 1 KB | — | ✓ | 3rd |
| https://www.birmingham.ac.uk/_s1t51Q_e03e1021-8a96-4a74-83eb-b7ac597b2ec5/static/modern/js/9912.6f4b319dd088322193b5.mjs | 3 KB | — | ✓ | 3rd |
| https://www.birmingham.ac.uk/_s1t51Q_e03e1021-8a96-4a74-83eb-b7ac597b2ec5/static/modern/js/features-composer-ComposerWrapper.a0da5f9364aa8b141e84.mjs | 3 KB | — | ✓ | 3rd |
| https://www.birmingham.ac.uk/_s1t51Q_e03e1021-8a96-4a74-83eb-b7ac597b2ec5/static/modern/js/features-heroCarousel-heroCarousel.6125ded3f3ddbae73d92.mjs | 1 KB | — | ✓ | 3rd |
Consider code splitting or tree shaking to reduce unused code.
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.
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.
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.
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.
This bundle has high unused code — code-split or tree-shake to ship only what executes.
Source: web.dev / Lighthouse coverage
FPage Weight InventoryAction57 resources · 1.5 MB · 412 KB savings availableFIX
~412.4 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 57 resources | 1.5 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
BPage Weight Budget1.5 MB transferred, 57 requestsREVIEW
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.
Source: web.dev
CGreen HostingActionWhether the site is served from green-energy infrastructureREVIEW
Green Hosting
No green hosting detected
A+Text CompressionAll text resources are compressedPASS
AImage Optimization17 images, 0 KB saveablePASS
A+Font Loading4 fonts (96 KB)PASS
Web fonts
4
96 KB total
Render-blocking
0
of 4
Dominant font-display
swap
Most common across fonts
Font loading timeline
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+Resource CachingAll resources properly cachedPASS
A+Critical Rendering PathNo render-blocking resourcesPASS
A+Resource Hints6 hints, 0 missing preconnectsPASS
Current Resource Hints
6 resource hints configured
A+Render-Blocking ResourcesNo render-blocking resources detectedPASS
A+Third-Party ResourcesNo third-party resources detectedPASS
Network Waterfall57 requests over 1989msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.birmingham.ac.uk www.birmingham.ac.uk | Other | 1107ms | 399 KB | 52% | £16/mo | Costly |
Unattributable Unattributable | Other | 885ms | 0 KB | — | £13/mo | Costly |
www.birmingham.ac.uk www.birmingham.ac.uk | Other | 525ms | 36 KB | — | £8/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 465ms | 200 KB | 32% | £7/mo | Costly |
cc.cdn.civiccomputing.com cc.cdn.civiccomputing.com | Other | 194ms | 123 KB | 47% | £3/mo | Optional |
These scripts may cost more than they're worth
- www.birmingham.ac.uk adds 1107ms and costs ~£16/month
- Unattributable adds 885ms and costs ~£13/month
- www.birmingham.ac.uk adds 525ms and costs ~£8/month
- Google Tag Manager adds 465ms and costs ~£7/month
100% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.
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.birmingham.ac.uk takes 1107ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
52% of www.birmingham.ac.uk's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
Unattributable takes 885ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.birmingham.ac.uk takes 525ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 465ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev