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.
861 ms
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
1.54 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
96 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.000
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
2.03 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.
2.95 s
Page Load Progression
FPage Weight BudgetAction3.8 MB transferred, 96 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
DThird-Party ImpactAction100% third-party, 0 ms blockingFIX
DPage Weight InventoryAction96 resources · 3.8 MB · 283 KB savings availableFIX
~282.8 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 96 resources | 3.8 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
BImage Optimization42 images, 0 KB saveableREVIEW
CJS Execution CostAction1796ms total JS executionREVIEW
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://cdn.ketchjs.com/ketchtag/stable/v2.12/ketch-sdk.js | 528ms | 415ms | 94ms | 3rd |
| Unattributable | 306ms | 23ms | 0ms | 3rd |
| https://cdn.privacy.paramount.com/dist/optanon-v2.0.0.js | 287ms | 263ms | 3ms | 3rd |
| https://www.cbsnews.com/ | 256ms | 9ms | 2ms | 3rd |
| https://www.cbsnews.com/fly/bundles/cbsnewscore/js-build/main.video-embed.js?v=296763317a51cab90faa73f1bb146d5c | 183ms | 143ms | 30ms | 3rd |
| https://www.cbsnews.com/fly/bundles/cbsnewscore/js-build/main.responsive.js?v=296763317a51cab90faa73f1bb146d5c | 118ms | 103ms | 1ms | 3rd |
| https://www.cbsnews.com/fly/bundles/cbsnewscore/js-build/main.js?v=296763317a51cab90faa73f1bb146d5c | 117ms | 84ms | 4ms | 3rd |
CJS BundlesAction17 scripts, 283 KB unusedREVIEW
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://cdn.ketchjs.com/ketchtag/stable/v2.12/ketch-sdk.js | 0 KB | 107 KB (42%) | ✓ | 3rd |
| https://cdn.ketchjs.com/ketchtag/stable/v2.12/ketch-sdk.js | 257 KB | 107 KB (42%) | ✓ | 3rd |
| https://disco.headliner.link/d/cbsnews/web/js/widget.js | 46 KB | 38 KB (82%) | ✓ | 3rd |
| https://www.cbsnews.com/fly/bundles/cbsnewscore/js-build/main.js?v=296763317a51cab90faa73f1bb146d5c | 60 KB | 31 KB (51%) | ✓ | 3rd |
| https://www.cbsnews.com/fly/bundles/cbsnewscore/js-build/main.video-embed.js?v=296763317a51cab90faa73f1bb146d5c | 0 KB | — | ✓ | 3rd |
| https://global.ketchcdn.com/web/v3/config/cbs_news/cbsnews/boot.js | 5 KB | — | ✓ | 3rd |
| https://www.cbsnews.com/fly/bundles/cbsnewscore/js-build/managers/adapter-live-headline-rundown.js?v=296763317a51cab90faa73f1bb146d5c | 1 KB | — | ✓ | 3rd |
| https://www.cbsnews.com/fly/bundles/cbsnewscore/js-build/components/viewability.js?v=296763317a51cab90faa73f1bb146d5c | 2 KB | — | ✓ | 3rd |
| https://cdn.privacy.paramount.com/dist/optanon-v2.0.0.js | 9 KB | — | ✓ | 3rd |
| https://cdn.privacy.paramount.com/dist/optanon-v2.0.0.js | 0 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
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 Loading8 fonts (135 KB)PASS
Web fonts
8
135 KB total
Render-blocking
0
of 8
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 Waterfall96 requests over 2305msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
cdn.ketchjs.com cdn.ketchjs.com | Other | 528ms | 0 KB | 42% | $10/mo | Costly |
Unattributable Unattributable | Other | 306ms | 0 KB | — | $6/mo | Costly |
cdn.privacy.paramount.com cdn.privacy.paramount.com | Other | 287ms | 0 KB | — | $5/mo | Costly |
www.cbsnews.com www.cbsnews.com | Other | 256ms | 247 KB | — | $5/mo | Costly |
www.cbsnews.com www.cbsnews.com | Other | 183ms | 0 KB | — | $3/mo | Optional |
www.cbsnews.com www.cbsnews.com | Other | 118ms | 13 KB | — | $2/mo | Optional |
www.cbsnews.com www.cbsnews.com | Other | 117ms | 60 KB | 51% | $2/mo | Optional |
These scripts may cost more than they're worth
- cdn.ketchjs.com adds 528ms and costs ~$10/month
- Unattributable adds 306ms and costs ~$6/month
- cdn.privacy.paramount.com adds 287ms and costs ~$5/month
- www.cbsnews.com adds 256ms and costs ~$5/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
cdn.ketchjs.com takes 528ms 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 306ms 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
cdn.privacy.paramount.com takes 287ms 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.cbsnews.com takes 256ms 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
51% of www.cbsnews.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