https://www.campusone.co.uk
Performance
· 27 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.SCORE
86
GRADE
B
FIX
2
REVIEW
6
PASS
15
INFO
4
Performance-focused optimization plan with CWV assessment, top offenders, and time estimates
47
97
100
92
First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.
3.26 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
11.71 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
637 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.
6.26 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.
11.91 s
Page Load Progression
Checks
2715 PASS 6 REVIEW 2 FIX
DPage Weight BudgetAction2.1 MB transferred, 59 requestsFIX
Page Weight Budget
Action2.1 MB transferred, 59 requests
2.1 MB transferred, 59 requests
Info::
Page weighs 4.5 MB (2.1 MB transferred)
Warning::
JavaScript is 744 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 744 KB
Info::
Fonts are 341 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 341 KB
Info::
59 HTTP requests
Info::
Estimated 0.44 g CO2 per page load
2.1 MB transferred
59 requests
0.44 g CO2 per page load
Images 843.3 KiB 39%
JavaScript 743.6 KiB 34%
Fonts 341.0 KiB 16%
Other 143.3 KiB 7%
HTML 58.5 KiB 3%
CSS 31.2 KiB 1%
Other 0 B 0%
0 2.4 MB 4.9 MB
Approaching limit
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
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
FJS Execution CostAction4628ms total JS executionFIX
JS Execution Cost
Action4628ms total JS execution
4628ms total JS execution
Warning::
https://www.campusone.co.uk/: 2174ms CPU time
Warning::
https://www.campusone.co.uk/_next/static/chunks/0v...: 1428ms CPU time
Warning::
Unattributable: 382ms CPU time
Warning::
https://www.googletagmanager.com/gtag/js?id=G-EJ2H...: 271ms CPU time
Info::
https://www.campusone.co.uk/_next/static/chunks/0f...: 168ms CPU time
Info::
Third-party scripts: 409ms (9% of total)
Main Thread Breakdown
Other 38% Script Evaluation 27% Style & Layout 16% Rendering 12% Script Parsing & Compilation 5%
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.campusone.co.uk/ | 2174ms | 10ms | 24ms | 1st |
| https://www.campusone.co.uk/_next/static/chunks/0v5ii6_5p1xpg.js | 1428ms | 800ms | 19ms | 1st |
| Unattributable | 382ms | 18ms | 0ms | 1st |
| https://www.googletagmanager.com/gtag/js?id=G-EJ2HEWMTPG&cx=c>m=4e6as1 | 271ms | 228ms | 42ms | 3rd |
| https://www.campusone.co.uk/_next/static/chunks/0fs0pypy6linu.js | 168ms | 9ms | 79ms | 1st |
| https://www.googletagmanager.com/gtm.js?id=GTM-TM6SGRS4 | 137ms | 106ms | 26ms | 3rd |
| https://www.campusone.co.uk/_next/static/chunks/1vykdafo07ed6.js | 67ms | 43ms | 14ms | 1st |
CJS BundlesAction20 scripts, 163 KB unusedREVIEW
JS Bundles
Action20 scripts, 163 KB unused
20 scripts, 163 KB unused
Warning::
https://www.googletagmanager.com/gtag/js?id=G-EJ2H...: 75 KB unused (42%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-TM6...: 62 KB unused (50%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.campusone.co.uk/_next/static/chunks/0v...: 26 KB unused (38%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 163 KB
163 KB unused JavaScript
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.googletagmanager.com/gtag/js?id=G-EJ2HEWMTPG&cx=c>m=4e6as1 | 177 KB | 75 KB (42%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-TM6SGRS4 | 124 KB | 62 KB (50%) | ✓ | 3rd |
| https://www.campusone.co.uk/_next/static/chunks/0v5ii6_5p1xpg.js | 70 KB | 26 KB (38%) | ✓ | 1st |
| https://www.campusone.co.uk/_next/static/chunks/3xbuqf82eihvn.js | 8 KB | — | ✓ | 1st |
| https://www.campusone.co.uk/_next/static/chunks/0uqn2kgew71cn.js | 14 KB | — | ✓ | 1st |
| https://www.campusone.co.uk/_next/static/chunks/1vykdafo07ed6.js | 43 KB | — | ✓ | 1st |
| https://www.campusone.co.uk/_next/static/chunks/turbopack-2noawjncj7c7z.js | 4 KB | — | ✓ | 1st |
| https://www.campusone.co.uk/_next/static/chunks/0oz66_9wndt57.js | 4 KB | — | ✓ | 1st |
| https://www.campusone.co.uk/_next/static/chunks/430yp0jar2a2m.js | 6 KB | — | ✓ | 1st |
| https://www.campusone.co.uk/_next/static/chunks/3_hvllj5rf9uy.js | 10 KB | — | ✓ | 1st |
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
BMain HTML Cache-ControlCache-Control present but without max-ageREVIEW
Main HTML Cache-Control
Cache-Control present but without max-age
Cache-Control present but without max-age
Info::
Main HTML Cache-Control has no max-age: s-maxage=3600, stale-while-revalidate=31532400
Got: s-maxage=3600, stale-while-revalidate=31532400
BServer-Timing ObservabilityNo Server-Timing header foundREVIEW
Server-Timing Observability
No Server-Timing header found
No Server-Timing header found
Info::
No Server-Timing header found
Server-Timing exposes backend timing breakdowns to browser DevTools (e.g., `db: 45ms; render: 120ms; cache: 2ms`). Useful for diagnosing slow pages without backend log access. Most modern frameworks (Next.js, Cloudflare Workers, Fastly) emit it automatically; absence on a managed platform usually means telemetry headers are stripped at the edge.
CPage Weight InventoryAction59 resources · 2.1 MB · 163 KB savings availableREVIEW
Page Weight Inventory
Action59 resources · 2.1 MB · 163 KB savings available
59 resources · 2.1 MB · 163 KB savings available
Warning::
Page weight 2.1 MB exceeds 1 MB target by 1.1 MB
Got: 2.1 MB Expected: ≤ 1 MB
Info::
~163 KB of savings available
Info::
7 third-party resources (15% of weight)
Info::
1 resources over 200KB
59 resources · 2.1 MiB · 7 third-party 1.1 MiB over 1MB target
Image 39% · 843.3 KiB
JavaScript 34% · 743.6 KiB
Font 16% · 341.0 KiB
Other 7% · 143.3 KiB
Document 3% · 58.5 KiB
CSS 1% · 31.2 KiB
~163.1 KiB of savings available
Remove unused JavaScript: 163.1 KiB
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 59 resources | 2.1 MiB | ||||||
BJavaScript Blocking2 JS blocking issue(s) detectedREVIEW
JavaScript Blocking
2 JS blocking issue(s) detected
2 JS blocking issue(s) detected
Warning::
4 render-blocking <script src> tag(s) without async/defer
Each `<script src=...>` without `async`, `defer`, or `type="module"` blocks HTML parsing while the browser fetches and executes it. The block lasts the entire round-trip + execution time -- on slow networks this translates directly into LCP delay. Add `defer` (executes after parse, in source order) for scripts that interact with the DOM, or `async` (executes whenever ready) for analytics / independent scripts. Module scripts (`type="module"`) are deferred by default.
Warning::
Total JS execution time is 4.6 s -- over the 3.5s budget
Total JavaScript execution (parse + compile + run) across all scripts exceeds 3.5 seconds. On low-end devices that becomes 7-15+ seconds and shows up directly in TBT and INP. Reduce by: tree-shaking unused dependencies, code-splitting (dynamic `import()`), removing or deferring third-party tracking, and replacing heavy frameworks where they're not needed.
BHTTP Cachings-maxage=3600, stale-while-revalidate=31532400REVIEW
HTTP Caching
s-maxage=3600, stale-while-revalidate=31532400
s-maxage=3600, stale-while-revalidate=31532400
Info::
Cache-Control header is set
Got: s-maxage=3600, stale-while-revalidate=31532400
Info::
CDN TTL: 1 hour (s-maxage=3600)
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control
s-maxage=3600, stale-while-revalidate=31532400
| Directive | Value | Meaning |
|---|---|---|
| s-maxage | 3600 | CDN caches for 1 hour |
| stale-while-revalidate | 31532400 | Serve stale for 52 weeks while fetching fresh |
A+Third-Party Impact15% third-party, 0 ms blockingPASS
Third-Party Impact
15% third-party, 0 ms blocking
15% third-party, 0 ms blocking
Info::
Third-party code accounts for 15% of page weight (327.2 KiB of 2.1 MiB)
Info::
Third-party blocking time is low (0 ms)
85%
15%
First-party Third-party
A+Text CompressionAll text resources are compressedPASS
Text Compression
All text resources are compressed
All text resources are compressed
Info::
All text resources are compressed
All text resources are properly compressed.
AImage Optimization20 images, 0 KB saveablePASS
Image Optimization
20 images, 0 KB saveable
20 images, 0 KB saveable
Info::
All images are well-optimized
20 images 843 KB
0 oversized -0 KB
3 legacy format
0 missing dimensions CLS risk
A+Font Loading5 fonts (341 KB)PASS
Font Loading
5 fonts (341 KB)
5 fonts (341 KB)
Info::
5 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
5
341 KB total
Render-blocking
0
of 5
Dominant font-display
swap
Most common across fonts
Font loading timeline
Transfer FOIT (block) FOUT (swap)
791bf8c4bb753ed6-s.p.0g... woff2 swap
Size 66 KB
Load time 340 ms
Start 210 ms
Risk FOUT — text flashes from fallback to web font
8010b10db0d5feb2-s.p.1q... woff2 swap
Size 80 KB
Load time 348 ms
Start 211 ms
Risk FOUT — text flashes from fallback to web font
a85fe84266768609-s.p.0h... woff2 swap
Size 73 KB
Load time 326 ms
Start 212 ms
Risk FOUT — text flashes from fallback to web font
inter-latin.woff2 woff2 swap
Size 48 KB
Load time 322 ms
Start 212 ms
Risk FOUT — text flashes from fallback to web font
a85fe84266768609-s.0h6i... woff2 swap
Size 73 KB
Load time 311 ms
Start 352 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+Resource CachingAll resources properly cachedPASS
Resource Caching
All resources properly cached
All resources properly cached
Info::
No caching issues found
All static resources have appropriate caching headers.
A+Critical Rendering PathNo render-blocking resourcesPASS
Critical Rendering Path
No render-blocking resources
No render-blocking resources
Info::
No render-blocking resources detected
A+Resource Hints9 hints, 0 missing preconnectsPASS
Resource Hints
9 hints, 0 missing preconnects
9 hints, 0 missing preconnects
Info::
Page uses 9 resource hint(s)
Current Resource Hints
preconnect—
preload 9
dns-prefetch—
prefetch—
9 resource hints configured
A+HTTP/3 (QUIC)HTTP/3 advertised via Alt-SvcPASS
HTTP/3 (QUIC)
HTTP/3 advertised via Alt-Svc
HTTP/3 advertised via Alt-Svc
Info::
HTTP/3 (QUIC) is supported
First-load mobile users on cellular networks see meaningful latency improvements with HTTP/3. The QUIC transport collapses TLS + TCP handshakes into one and recovers faster from packet loss.
A+Document CompressionDocument response uses brotliPASS
Document Compression
Document response uses brotli
Document response uses brotli
Info::
Main HTML response uses brotli (Content-Encoding: br)
Brotli is the best text-compression algorithm for general use, ~20% smaller than gzip on average (40% on smaller files). Modern browsers all support it.
A+LCP Image PreloadLCP preload audit not availablePASS
LCP Image Preload
LCP preload audit not available
LCP preload audit not available
Info::
LCP image preload audit not available for this scan
A+Server Response Intelligence2 server-response signal(s) detectedPASS
Server Response Intelligence
2 server-response signal(s) detected
2 server-response signal(s) detected
Info::
`Vary` header declared: rsc, next-router-state-tree, next-router-prefetch, next-router-segment-prefetch,...
The page declares a `Vary` header, telling downstream caches which request headers the response varies on. Critical for content-negotiated responses (compression, language, cookies, device class).
Info::
No `ETag` or `Last-Modified` -- conditional GET not supported
Without either header, browsers can't issue conditional GETs and refresh always re-downloads the full response body even when nothing changed. Add `ETag: "<hash>"` (or `Last-Modified: <date>`) on cacheable responses; the server returns 304 Not Modified when the client's cached copy is still valid, saving bandwidth.
A+Render-Blocking ResourcesNo render-blocking resources detectedPASS
Render-Blocking Resources
No render-blocking resources detected
No render-blocking resources detected
Info::
No render-blocking resources detected in <head>
A+Third-Party ResourcesNo third-party resources detectedPASS
Third-Party Resources
No third-party resources detected
No third-party resources detected
A+CSS Performance DepthNo CSS performance depth issues detectedPASS
CSS Performance Depth
No CSS performance depth issues detected
No CSS performance depth issues detected
Info::
No CSS performance depth issues detected
A+Green HostingWhether the site is served from green-energy infrastructurePASS
Green Hosting
Whether the site is served from green-energy infrastructure
Green Hosting
This site is hosted on green energy infrastructure
Provider: Cloudflare
Asset CompressionNo text asset hosts to measureINFO
Asset Compression
No text asset hosts to measure
No text asset hosts to measure
Info::
No third-party or subdomain host served enough text assets to measure
Asset compression is measured per host, from one HEAD request against a sampled resource. Pages that serve all their JS and CSS from the document's own origin are covered by the document compression check instead.
Network Waterfall59 requests over 1778msINFO
Network Waterfall
59 requests over 1778ms
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
9% of JavaScript execution is third-party
First-party Third-party 409ms · 301KB · £4/mo
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
Google Tag Manager www.googletagmanager.com | Tag Manager | 271ms | 177 KB | 42% | £3/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 137ms | 124 KB | 50% | £1/mo | Optional |
Google Tag Manager
Tag Manager
Execution 271ms
Transfer 177 KB
Unused 42%
Monthly Cost £3/mo
Google Tag Manager
Tag Manager
Execution 137ms
Transfer 124 KB
Unused 50%
Monthly Cost £1/mo
These scripts may cost more than they're worth
- Google Tag Manager adds 271ms and costs ~£3/month
Google Tag Manager takes 271ms 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
50% of Google Tag Manager'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
Image Optimization42 images, 830 KB total, 497 KB wastedINFO
Image Optimization
42 images, 830 KB total, 497 KB wasted
Image Optimization Audit
Total Images
42
Total Size
830 KB
Oversized
3
Wasted
497 KB
8 missing dimensions 4 missing lazy loading
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.