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.
949 ms
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
1.63 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
112 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.125
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
1.91 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.
5.07 s
Page Load Progression
375 ms 750 ms
1.1 s
1.5 s 1.9 s
2.2 s 2.6 s 3.0 sFPage Weight BudgetAction8.0 MB transferred, 237 requestsFIX
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
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
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
DJS Execution CostAction2221ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| Unattributable | 632ms | 114ms | 0ms | 3rd |
| https://www.fox.com/_next/static/chunks/1255-f3876c9da16a7317.js | 291ms | 265ms | 13ms | 3rd |
| https://www.fox.com/ | 235ms | 18ms | 40ms | 3rd |
| https://www.fox.com/_next/static/chunks/4bd1b696-182b6b13bdad92e3.js | 197ms | 137ms | 25ms | 3rd |
| https://cdn.ketchjs.com/ketchtag/stable/v2.12/ketch-sdk.js | 166ms | 122ms | 43ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=AW-17385582396&cx=c>m=4e64k0 | 123ms | 99ms | 12ms | 3rd |
| https://www.fox.com/_next/static/chunks/webpack-8ba319e07e562464.js | 119ms | 46ms | 0ms | 3rd |
| https://www.fox.com/_next/static/chunks/1454f9c2-1deac677e9c47955.js | 117ms | 99ms | 6ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-NK3RRW5Z | 100ms | 84ms | 10ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=DC-14772086&cx=c>m=4e64k0 | 99ms | 88ms | 10ms | 3rd |
Showing top 10 of 12 scripts
FJS BundlesAction73 scripts, 539 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://cdn.ketchjs.com/ketchtag/stable/v2.12/ketch-sdk.js | 259 KB | 156 KB (60%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-NK3RRW5Z | 143 KB | 71 KB (49%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=AW-17385582396&cx=c>m=4e64k0 | 140 KB | 55 KB (39%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=DC-14772086&cx=c>m=4e64k0 | 131 KB | 54 KB (41%) | ✓ | 3rd |
| https://www.fox.com/_next/static/chunks/431.3d999772e7fae8b0.js | 66 KB | 37 KB (56%) | ✓ | 3rd |
| https://cdn.us.heap-api.com/v5/heapjs-static/5.3.12/core/heap.js | 82 KB | 37 KB (45%) | ✓ | 3rd |
| https://www.fox.com/_next/static/chunks/5061-d394c11ee9429c9b.js | 65 KB | 36 KB (56%) | ✓ | 3rd |
| https://www.fox.com/_next/static/chunks/3916-6bebacc07c9b3958.js | 40 KB | 33 KB (83%) | ✓ | 3rd |
| https://apps.rokt-api.com/js/v2/us2-67e858d646c85846b52e42b135745325/app.js?env=0& | 58 KB | 33 KB (57%) | ✓ | 3rd |
| https://www.fox.com/_next/static/chunks/1454f9c2-1deac677e9c47955.js | 65 KB | 28 KB (42%) | ✓ | 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 InventoryAction237 resources · 8.0 MB · 539 KB savings availableFIX
~538.5 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 237 resources | 8.0 MiB | ||||||
DHTTP CachingActionno-store (uncacheable)FIX
no-store, max-age=0
| Directive | Value | Meaning |
|---|---|---|
| no-store | — | Never cache this response |
| max-age | 0 | Cache for 0 seconds |
BImage Optimization62 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 (172 KB)PASS
Web fonts
5
172 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 Waterfall237 requests over 3533msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
Unattributable Unattributable | Other | 632ms | 0 KB | — | €7/mo | Costly |
www.fox.com www.fox.com | Other | 291ms | 45 KB | — | €3/mo | Costly |
www.fox.com www.fox.com | Other | 235ms | 93 KB | — | €3/mo | Costly |
www.fox.com www.fox.com | Other | 197ms | 53 KB | — | €2/mo | Optional |
cdn.ketchjs.com cdn.ketchjs.com | Other | 166ms | 259 KB | 60% | €2/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 123ms | 140 KB | 39% | €1/mo | Optional |
www.fox.com www.fox.com | Other | 119ms | 2 KB | — | €1/mo | Optional |
www.fox.com www.fox.com | Other | 117ms | 65 KB | 42% | €1/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 100ms | 143 KB | 49% | €1/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 99ms | 131 KB | 41% | €1/mo | Optional |
Amplitude cdn.amplitude.com | Analytics | 80ms | 47 KB | — | €1/mo | Optional |
cdn.us.heap-api.com cdn.us.heap-api.com | Other | 63ms | 82 KB | 45% | €1/mo | Optional |
These scripts may cost more than they're worth
- Unattributable adds 632ms and costs ~€7/month
- www.fox.com adds 291ms and costs ~€3/month
- www.fox.com adds 235ms and costs ~€3/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
Unattributable takes 632ms 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.fox.com 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
www.fox.com takes 235ms 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
60% of cdn.ketchjs.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