Performance
· 15 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.
1.26 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
2.96 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
56 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.025
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
2.63 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.
3.91 s
Page Load Progression
FPage Weight BudgetAction2.7 MB transferred, 158 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
DThird-Party ImpactAction100% third-party, 0 ms blockingFIX
FJS BundlesAction52 scripts, 954 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://cdn.ampproject.org/v0.js | 72 KB | 151 KB (54%) | ✓ | 3rd |
| https://cdn.ampproject.org/v0.js | 0 KB | 151 KB (54%) | ✓ | 3rd |
| https://s2-prod.mirror.co.uk/@trinitymirrordigital/auth-ui/auth-ui.min.js?v=bc255d9af177385f49e8d91b2f1cdfa9 | 133 KB | 80 KB (61%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-M3TH25P | 191 KB | 67 KB (35%) | ✓ | 3rd |
| https://cdn.amplitude.com/libs/analytics-browser-gtm-wrapper-2.36.8.min.js.br | 80 KB | 66 KB (84%) | ✓ | 3rd |
| https://premium.express.co.uk/js/dist/app-pp20260212.min.js | 91 KB | 59 KB (65%) | ✓ | 3rd |
| https://s2-prod.mirror.co.uk/@trinitymirrordigital/withnail/scriptsCore/js/withnail.min.js?v=2cadb05903db3564e96376d7c9404ba4 | 91 KB | 56 KB (62%) | ✓ | 3rd |
| https://cmp.inmobi.com/tcfv2/61/cmp2ui-en.js | 110 KB | 52 KB (48%) | ✓ | 3rd |
| https://cmp.inmobi.com/tcfv2/61/cmp2.js?referer=www.mirror.co.uk | 116 KB | 50 KB (52%) | ✓ | 3rd |
| https://s2-prod.mirror.co.uk/@trinitymirrordigital/withnail/tags/js/tags.min.js?v=2e1b663e4c838a4fb754e3efc78ebdc2 | 87 KB | 41 KB (48%) | ✓ | 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 InventoryAction158 resources · 2.7 MB · 954 KB savings availableFIX
~954.1 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 158 resources | 2.7 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
BImage Optimization47 images, 0 KB saveableREVIEW
CJS Execution CostAction1826ms total JS executionREVIEW
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.mirror.co.uk/ | 545ms | 64ms | 21ms | 3rd |
| Unattributable | 291ms | 56ms | 0ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-M3TH25P | 207ms | 178ms | 18ms | 3rd |
| https://cdn.ampproject.org/v0.js | 189ms | 89ms | 6ms | 3rd |
| https://cmp.inmobi.com/tcfv2/61/cmp2ui-en.js | 119ms | 78ms | 11ms | 3rd |
| https://s2-prod.mirror.co.uk/@trinitymirrordigital/withnail/tags/js/runForceReconsent.min.js?v=effa25bbffd498101adfd4cc236cdd33 | 118ms | 47ms | 6ms | 3rd |
| https://cmp.inmobi.com/tcfv2/61/cmp2.js?referer=www.mirror.co.uk | 97ms | 72ms | 13ms | 3rd |
| https://s2-prod.mirror.co.uk/@trinitymirrordigital/withnail/scriptsCore/js/withnail.min.js?v=2cadb05903db3564e96376d7c9404ba4 | 76ms | 54ms | 7ms | 3rd |
| https://s2-prod.mirror.co.uk/@trinitymirrordigital/withnail/tags/js/tags.min.js?v=2e1b663e4c838a4fb754e3efc78ebdc2 | 65ms | 48ms | 9ms | 3rd |
| https://s2-prod.mirror.co.uk/@trinitymirrordigital/auth-ui/auth-ui.min.js?v=bc255d9af177385f49e8d91b2f1cdfa9 | 60ms | 37ms | 12ms | 3rd |
Showing top 10 of 11 scripts
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 Loading4 fonts (311 KB)PASS
Web fonts
4
311 KB total
Render-blocking
0
of 4
Dominant font-display
swap
Most common across fonts
Font loading timeline
- 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 ~117 KB and ~234 ms
A+Resource CachingAll resources properly cachedPASS
A+Critical Rendering PathNo render-blocking resourcesPASS
A+Resource HintsNo optimization neededPASS
Network Waterfall158 requests over 8658msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.mirror.co.uk www.mirror.co.uk | Other | 545ms | 141 KB | — | £3/mo | Costly |
Unattributable Unattributable | Other | 291ms | 0 KB | — | £2/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 207ms | 191 KB | 35% | £1/mo | Costly |
cdn.ampproject.org cdn.ampproject.org | Other | 189ms | 0 KB | 54% | £1/mo | Optional |
cmp.inmobi.com cmp.inmobi.com | Other | 119ms | 110 KB | 48% | £1/mo | Optional |
s2-prod.mirror.co.uk s2-prod.mirror.co.uk | Other | 118ms | 49 KB | 59% | £1/mo | Optional |
cmp.inmobi.com cmp.inmobi.com | Other | 97ms | 116 KB | 52% | £0/mo | Optional |
s2-prod.mirror.co.uk s2-prod.mirror.co.uk | Other | 76ms | 91 KB | 62% | £0/mo | Optional |
s2-prod.mirror.co.uk s2-prod.mirror.co.uk | Other | 65ms | 87 KB | 48% | £0/mo | Optional |
s2-prod.mirror.co.uk s2-prod.mirror.co.uk | Other | 60ms | 133 KB | 61% | £0/mo | Optional |
feliz-web.data.tm-awx.com feliz-web.data.tm-awx.com | Other | 59ms | 7 KB | — | £0/mo | Optional |
These scripts may cost more than they're worth
- www.mirror.co.uk adds 545ms and costs ~£3/month
- Unattributable adds 291ms and costs ~£2/month
- Google Tag Manager adds 207ms and costs ~£1/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.mirror.co.uk takes 545ms 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
Unattributable takes 291ms 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 207ms 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
54% of cdn.ampproject.org'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
59% of s2-prod.mirror.co.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
52% of cmp.inmobi.com'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
62% of s2-prod.mirror.co.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
61% of s2-prod.mirror.co.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