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.
1.70 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
5.50 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
207 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.002
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
2.51 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.
5.65 s
Page Load Progression
FPage Weight BudgetAction3.0 MB transferred, 93 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
DThird-Party ImpactAction100% third-party, 0 ms blockingFIX
FJS BundlesAction42 scripts, 693 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://lpcdn.lpsnmedia.net/le_unified_window/10.47.0-release_2318786578/desktopEmbedded.js?version=10.47.0-release_2318786578 | 265 KB | 182 KB (69%) | ✓ | 3rd |
| https://www.sky.com/dt_product_discovery/_next/static/chunks/pages/_app-77835c234ce93925.js | 223 KB | 125 KB (58%) | ✓ | 3rd |
| https://www.sky.com/metrics/gtm.js?id=GTM-MRK43FPT | 181 KB | 89 KB (51%) | ✓ | 3rd |
| https://www.sky.com/dt_product_discovery/_next/static/chunks/framework-62a58fb48f169ce1.js | 120 KB | 72 KB (63%) | ✓ | 3rd |
| https://assets.adobedtm.com/launch-ENd6c8a33809694f8684febbdf83b39af8.min.js | 206 KB | 61 KB (30%) | ✓ | 3rd |
| https://lptag.liveperson.net/lptag/api/account/66659534/configuration/applications/taglets/.jsonp?v=2.0&df=undefined&s=tagletSection&b=undefined | 125 KB | 50 KB (44%) | ✓ | 3rd |
| https://assets.sky.com/bundles/masthead/bundle-6fc85e27.js | 78 KB | 49 KB (63%) | ✓ | 3rd |
| https://cdn.optimizely.com/public/2900460605/s/snippet_discovery_masthead.js | 111 KB | 43 KB (39%) | ✓ | 3rd |
| https://www.sky.com/consent-v2/wrapperMessagingWithoutDetection.js | 59 KB | 23 KB (43%) | ✓ | 3rd |
| https://cdn.branch.io/branch-latest.min.js | 23 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 InventoryAction93 resources · 3.0 MB · 693 KB savings availableFIX
~693.4 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 93 resources | 3.0 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
CJS Execution CostAction1479ms total JS executionREVIEW
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.sky.com/dt_product_discovery/_next/static/chunks/framework-62a58fb48f169ce1.js | 361ms | 302ms | 12ms | 3rd |
| Unattributable | 275ms | 11ms | 0ms | 3rd |
| https://www.sky.com/ | 246ms | 14ms | 2ms | 3rd |
| https://www.sky.com/dt_product_discovery/_next/static/chunks/pages/_app-77835c234ce93925.js | 127ms | 99ms | 25ms | 3rd |
| https://assets.adobedtm.com/launch-ENd6c8a33809694f8684febbdf83b39af8.min.js | 110ms | 76ms | 30ms | 3rd |
| https://www.sky.com/metrics/gtm.js?id=GTM-MRK43FPT | 83ms | 67ms | 15ms | 3rd |
| https://assets.sky.com/bundles/masthead/bundle-6fc85e27.js | 81ms | 48ms | 11ms | 3rd |
| https://cdn.optimizely.com/public/2900460605/s/snippet_discovery_masthead.js | 74ms | 52ms | 20ms | 3rd |
| https://www.sky.com/consent-v2/wrapperMessagingWithoutDetection.js | 63ms | 52ms | 8ms | 3rd |
| https://lpcdn.lpsnmedia.net/le_unified_window/10.47.0-release_2318786578/desktopEmbedded.js?version=10.47.0-release_2318786578 | 60ms | 22ms | 38ms | 3rd |
CGreen HostingActionWhether the site is served from green-energy infrastructureREVIEW
Green Hosting
No green hosting detected
A+Text CompressionAll text resources are compressedPASS
A+Image Optimization12 images, 0 KB saveablePASS
A+Font Loading5 fonts (128 KB)PASS
Web fonts
5
128 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
A+Resource HintsNo optimization neededPASS
Network Waterfall93 requests over 4592msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.sky.com www.sky.com | Other | 361ms | 120 KB | 63% | £6/mo | Costly |
Unattributable Unattributable | Other | 275ms | 0 KB | — | £5/mo | Costly |
www.sky.com www.sky.com | Other | 246ms | 53 KB | — | £4/mo | Costly |
www.sky.com www.sky.com | Other | 127ms | 223 KB | 58% | £2/mo | Optional |
assets.adobedtm.com assets.adobedtm.com | Other | 110ms | 206 KB | 30% | £2/mo | Optional |
www.sky.com www.sky.com | Other | 83ms | 181 KB | 51% | £1/mo | Optional |
assets.sky.com assets.sky.com | Other | 81ms | 78 KB | 63% | £1/mo | Optional |
Optimizely cdn.optimizely.com | A/B Testing | 74ms | 111 KB | 39% | £1/mo | Optional |
www.sky.com www.sky.com | Other | 63ms | 59 KB | 43% | £1/mo | Optional |
lpcdn.lpsnmedia.net lpcdn.lpsnmedia.net | Other | 60ms | 265 KB | 69% | £1/mo | Optional |
These scripts may cost more than they're worth
- www.sky.com adds 361ms and costs ~£6/month
- Unattributable adds 275ms and costs ~£5/month
- www.sky.com adds 246ms and costs ~£4/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.sky.com takes 361ms 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
63% of www.sky.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
Unattributable takes 275ms 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.sky.com takes 246ms 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
58% of www.sky.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
51% of www.sky.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
63% of assets.sky.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
69% of lpcdn.lpsnmedia.net'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