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.
4.78 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
19.19 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
3.25 s
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.359
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
7.36 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.
24.50 s
Page Load Progression
FPage Weight BudgetAction3.8 MB transferred, 119 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
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Image bandwidth is high — modern formats (WebP/AVIF) and resizing typically cut it 50%+.
Source: web.dev
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 Execution CostAction8354ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.sky.com/dt_product_discovery/_next/static/chunks/framework-62a58fb48f169ce1.js | 1913ms | 1571ms | 61ms | 3rd |
| Unattributable | 1204ms | 57ms | 0ms | 3rd |
| https://www.sky.com/ | 1081ms | 72ms | 8ms | 3rd |
| https://assets.adobedtm.com/launch-ENd6c8a33809694f8684febbdf83b39af8.min.js | 592ms | 403ms | 162ms | 3rd |
| https://www.sky.com/dt_product_discovery/_next/static/chunks/pages/_app-77835c234ce93925.js | 511ms | 396ms | 93ms | 3rd |
| https://cdn.optimizely.com/public/2900460605/s/snippet_discovery_masthead.js | 428ms | 345ms | 52ms | 3rd |
| https://www.sky.com/metrics/gtm.js?id=GTM-MRK43FPT | 393ms | 326ms | 62ms | 3rd |
| https://assets.sky.com/bundles/masthead/bundle-6fc85e27.js | 310ms | 224ms | 39ms | 3rd |
| https://www.sky.com/consent-v2/wrapperMessagingWithoutDetection.js | 264ms | 220ms | 32ms | 3rd |
| https://lptag.liveperson.net/lptag/api/account/66659534/configuration/applications/taglets/.jsonp?v=2.0&df=undefined&s=tagletSection&b=undefined | 250ms | 196ms | 47ms | 3rd |
Showing top 10 of 21 scripts
FJS BundlesAction56 scripts, 742 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/mobileEmbedded.js?version=10.47.0-release_2318786578 | 263 KB | 181 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 | 86 KB (49%) | ✓ | 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://www.googletagmanager.com/gtag/js?id=not%20set&l=dataLayer | 85 KB | 56 KB (66%) | ✓ | 3rd |
| https://assets.sky.com/bundles/masthead/bundle-6fc85e27.js | 78 KB | 50 KB (65%) | ✓ | 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://cdn.optimizely.com/public/2900460605/s/snippet_discovery_masthead.js | 111 KB | 38 KB (35%) | ✓ | 3rd |
| https://www.sky.com/consent-v2/wrapperMessagingWithoutDetection.js | 59 KB | 23 KB (43%) | ✓ | 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 InventoryAction119 resources · 3.8 MB · 742 KB savings availableFIX
~742.2 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 119 resources | 3.8 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
BImage Optimization19 images, 0 KB saveableREVIEW
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 (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 Hints5 hints, 0 missing preconnectsPASS
Current Resource Hints
5 resource hints configured
A+Render-Blocking ResourcesNo render-blocking resources detectedPASS
A+Third-Party ResourcesNo third-party resources detectedPASS
Network Waterfall119 requests over 8668msINFO
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 | 1913ms | 120 KB | 63% | £33/mo | Costly |
Unattributable Unattributable | Other | 1204ms | 0 KB | — | £21/mo | Costly |
www.sky.com www.sky.com | Other | 1081ms | 53 KB | — | £19/mo | Costly |
assets.adobedtm.com assets.adobedtm.com | Other | 592ms | 206 KB | 30% | £10/mo | Costly |
www.sky.com www.sky.com | Other | 511ms | 223 KB | 58% | £9/mo | Costly |
Optimizely cdn.optimizely.com | A/B Testing | 428ms | 111 KB | 35% | £7/mo | Costly |
www.sky.com www.sky.com | Other | 393ms | 181 KB | 49% | £7/mo | Costly |
assets.sky.com assets.sky.com | Other | 310ms | 78 KB | 65% | £5/mo | Costly |
www.sky.com www.sky.com | Other | 264ms | 59 KB | 43% | £5/mo | Costly |
lptag.liveperson.net lptag.liveperson.net | Other | 250ms | 125 KB | 44% | £4/mo | Costly |
lpcdn.lpsnmedia.net lpcdn.lpsnmedia.net | Other | 232ms | 263 KB | 69% | £4/mo | Costly |
cdn.branch.io cdn.branch.io | Other | 195ms | 23 KB | — | £3/mo | Optional |
www.sky.com www.sky.com | Other | 155ms | 43 KB | — | £3/mo | Optional |
www.sky.com www.sky.com | Other | 145ms | 10 KB | — | £2/mo | Optional |
assets.adobedtm.com assets.adobedtm.com | Other | 134ms | 0 KB | — | £2/mo | Optional |
assets.adobedtm.com assets.adobedtm.com | Other | 122ms | 1 KB | — | £2/mo | Optional |
unpkg unpkg.com | CDN | 101ms | 0 KB | — | £2/mo | Optional |
lpcdn.lpsnmedia.net lpcdn.lpsnmedia.net | Other | 88ms | 15 KB | — | £2/mo | Optional |
content.zeotap.com content.zeotap.com | Other | 87ms | 32 KB | — | £2/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 86ms | 85 KB | 66% | £1/mo | Optional |
assets.adobedtm.com assets.adobedtm.com | Other | 62ms | 9 KB | — | £1/mo | Optional |
These scripts may cost more than they're worth
- www.sky.com adds 1913ms and costs ~£33/month
- Unattributable adds 1204ms and costs ~£21/month
- www.sky.com adds 1081ms and costs ~£19/month
- assets.adobedtm.com adds 592ms and costs ~£10/month
- www.sky.com adds 511ms and costs ~£9/month
- Optimizely adds 428ms and costs ~£7/month
- www.sky.com adds 393ms and costs ~£7/month
- assets.sky.com adds 310ms and costs ~£5/month
- www.sky.com adds 264ms and costs ~£5/month
- lptag.liveperson.net adds 250ms and costs ~£4/month
- lpcdn.lpsnmedia.net adds 232ms 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 1913ms 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 1204ms 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 1081ms 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 592ms 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 511ms 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
Optimizely takes 428ms 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 393ms 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.sky.com takes 310ms 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
65% 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
www.sky.com takes 264ms 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
lptag.liveperson.net takes 250ms 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
lpcdn.lpsnmedia.net takes 232ms 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
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
66% of Google Tag Manager'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