Performance
· 28 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.
3.67 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
7.76 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
1.43 s
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.370
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
7.97 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.
17.77 s
Page Load Progression
FPage Weight BudgetAction2.7 MB transferred, 163 requestsFIX
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
Subset fonts to include only used characters, or switch to system font stacks.
Font payload is large — subset to used glyphs only, or fall back to system fonts (zero load time).
Source: web.dev font loading
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.
Source: web.dev
FJS Execution CostAction5146ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.lycamobile.co.uk/_next/static/chunks/framework-25500088d8b22498.js | 972ms | 848ms | 17ms | 1st |
| Unattributable | 568ms | 11ms | 0ms | 1st |
| https://www.lycamobile.co.uk/_next/static/chunks/pages/_app-eaa6432c8502f70f.js | 541ms | 391ms | 139ms | 1st |
| https://www.lycamobile.co.uk/en/ | 457ms | 90ms | 7ms | 1st |
| https://www.googletagmanager.com/gtag/js?id=G-P52E9JTP7V&cx=c>m=4e6au1 | 349ms | 287ms | 59ms | 3rd |
| https://scripts.clarity.ms/0.8.77-beta/clarity.js | 326ms | 306ms | 8ms | 3rd |
| https://assets.adobedtm.com/9007b98fe545/821c9abd597c/launch-acb171025420.min.js | 319ms | 189ms | 77ms | 3rd |
| https://www.lycamobile.co.uk/_next/static/chunks/18711-5414c8a16c4615ad.js | 265ms | 215ms | 9ms | 1st |
| https://www.lycamobile.co.uk/cdn-cgi/challenge-platform/scripts/jsd/main.js?ray=a54b49cafa15dc71 | 251ms | 228ms | 3ms | 1st |
| https://www.lycamobile.co.uk/_next/static/chunks/76870.814c14dfb96c10a2.js | 232ms | 201ms | 1ms | 1st |
Showing top 10 of 18 scripts
FJS BundlesAction61 scripts, 600 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.lycamobile.co.uk/_next/static/chunks/pages/_app-eaa6432c8502f70f.js | 490 KB | 252 KB (52%) | ✓ | 1st |
| https://www.googletagmanager.com/gtag/js?id=G-P52E9JTP7V&cx=c>m=4e6au1 | 197 KB | 76 KB (39%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-WRQNFFFZ | 127 KB | 61 KB (48%) | ✓ | 3rd |
| https://www.lycamobile.co.uk/_next/static/chunks/24141-9b521af344399d83.js | 48 KB | 43 KB (93%) | ✓ | 1st |
| https://www.lycamobile.co.uk/_next/static/chunks/65524-fe97f2b637723349.js | 37 KB | 33 KB (95%) | ✓ | 1st |
| https://assets.adobedtm.com/9007b98fe545/821c9abd597c/launch-acb171025420.min.js | 152 KB | 33 KB (22%) | ✓ | 3rd |
| https://www.lycamobile.co.uk/_next/static/chunks/40366-10825ec590c80a79.js | 35 KB | 30 KB (91%) | ✓ | 1st |
| https://www.lycamobile.co.uk/_next/static/chunks/framework-25500088d8b22498.js | 69 KB | 27 KB (40%) | ✓ | 1st |
| https://www.lycamobile.co.uk/_next/static/chunks/55160-299f4560e73a3227.js | 30 KB | 23 KB (80%) | ✓ | 1st |
| https://www.lycamobile.co.uk/_next/static/chunks/main-e30ada0fb6f9f3ed.js | 43 KB | 22 KB (53%) | ✓ | 1st |
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 InventoryAction163 resources · 2.7 MB · 600 KB savings availableFIX
~600.1 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 163 resources | 2.7 MiB | ||||||
DHTTP CachingActionno-store (uncacheable)FIX
private, no-cache, no-store, max-age=0, must-revalidate
| Directive | Value | Meaning |
|---|---|---|
| private | — | Only browser cache, not CDN/proxy |
| no-cache | — | Cache but always revalidate first |
| no-store | — | Never cache this response |
| max-age | 0 | Cache for 0 seconds |
| must-revalidate | — | Must recheck with server after expiry |
BThird-Party Impact42% third-party, 0 ms blockingREVIEW
CImage OptimizationAction47 images, 0 KB saveableREVIEW
Set explicit width and height to prevent CLS.
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.
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.
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
BServer-Timing ObservabilityNo Server-Timing header foundREVIEW
CGreen HostingActionWhether the site is served from green-energy infrastructureREVIEW
Green Hosting
No green hosting detected
A+Text CompressionAll text resources are compressedPASS
A+Font Loading5 fonts (277 KB)PASS
Web fonts
5
277 KB total
Render-blocking
0
of 5
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
AResource Hints24 hints, 0 missing preconnectsPASS
Current Resource Hints
24 resource hints configured
preconnect already does the DNS lookup; adding dns-prefetch to the same origin is at best a no-op. Sample: https://cms-assets.ldsvcplatform.com, https://s3-eu-west-2.amazonaws.com. Remove the redundant dns-prefetch entries.
Performance issues directly impact user engagement and conversion rates.
The same href shouldn't appear in multiple hint rels -- one wins, the others are wasted markup and may confuse cache behavior. Sample: /_next/static/media/Account.ec46a854.svg (preload+preload), /_next/static/media/Cart.c7614522.svg (preload+preload), https://cms-assets.ldsvcplatform.com (preconnect+dns-prefetch) (+3 more).
Performance issues directly impact user engagement and conversion rates.
A+HTTP/3 (QUIC)HTTP/3 advertised via Alt-SvcPASS
A+Document CompressionDocument response uses brotliPASS
A+LCP Image PreloadLCP preload audit not availablePASS
A+Main HTML Cache-ControlMain HTML uses no-store -- correct for sensitive/dynamic contentPASS
A+Server Response Intelligence2 server-response signal(s) detectedPASS
A+Render-Blocking ResourcesNo render-blocking resources detectedPASS
A+Third-Party ResourcesNo third-party resources detectedPASS
AJavaScript Blocking1 JS blocking issue(s) detectedPASS
ACSS Performance Depth1 CSS depth issue(s) detectedPASS
Asset CompressionNo text asset hosts to measureINFO
Network Waterfall163 requests over 2908msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
Google Tag Manager www.googletagmanager.com | Tag Manager | 349ms | 197 KB | 39% | £4/mo | Costly |
Microsoft Clarity scripts.clarity.ms | Session Replay | 326ms | 25 KB | — | £3/mo | Costly |
assets.adobedtm.com assets.adobedtm.com | Other | 319ms | 152 KB | 22% | £3/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 131ms | 127 KB | 48% | £1/mo | Optional |
sc-static.net sc-static.net | Other | 95ms | 25 KB | — | £1/mo | Optional |
These scripts may cost more than they're worth
- Google Tag Manager adds 349ms and costs ~£4/month
- Microsoft Clarity adds 326ms and costs ~£3/month
- assets.adobedtm.com adds 319ms and costs ~£3/month
Google Tag Manager takes 349ms 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
Microsoft Clarity takes 326ms 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
assets.adobedtm.com takes 319ms 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
Real-User Performance (CrUX)Field metrics from the Chrome User Experience ReportINFO
Chrome User Experience (CrUX)
Real-user metrics from the Chrome UX Report (2026-10-05 — 2026-11-01)
LCP (p75)
1925 ms
82% good
INP (p75)
247 ms
65% good
CLS (p75)
0.320
34% good
FCP (p75)
1251 ms
TTFB (p75)
691 ms
Image Optimization100 images, 4 KB total, 0 KB wastedINFO
Image Optimization Audit
Total Images
100
Total Size
4 KB
Oversized
17