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Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
72
GRADE
C
FIX
4
REVIEW
2
PASS
6
INFO
2

Performance-focused optimization plan with CWV assessment, top offenders, and time estimates

Mobile Desktop
68
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
93
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
77
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
85
SEO Measures basic SEO optimizations: meta tags, crawlability, link text, and mobile friendliness.

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

1.39 s

Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.

1.90 s

Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.

344 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.003

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

2.31 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.

8.69 s

Page Load Progression

933 ms
1.9 s
2.8 s
3.7 s
4.7 s
5.6 s
6.5 s
7.5 s
Checks
14
6 PASS 2 REVIEW 4 FIX
F
Page Weight Budget
Action
11.6 MB transferred, 179 requests
FIX
11.6 MB transferred, 179 requests
Critical::
Page weighs 23.1 MB (11.6 MB transferred)
Warning::
JavaScript is 4.4 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 4.4 MB
Warning::
Images are 3.5 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 3.5 MB
Info::
Fonts are 221 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 221 KB
Warning::
179 HTTP requests — consider bundling or reducing
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
Info::
Estimated 2.4 g CO2 per page load
11.6 MB / 2.4 MB budget
11.6 MB transferred
179 requests
2.4 g CO2 per page load
JavaScript 4.4 MiB 38%
Images 3.5 MiB 30%
Other 2.8 MiB 24%
HTML 515.3 KiB 4%
Fonts 220.9 KiB 2%
Other 127.0 KiB 1%
CSS 40.4 KiB 0%
Other 25.9 KiB 0%
Other 7.3 KiB 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Over budget

Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.

Why this matters

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.

Why this matters

Image bandwidth is high — modern formats (WebP/AVIF) and resizing typically cut it 50%+.

Source: web.dev

Subset fonts to include only used characters, or switch to system font stacks.

Why this matters

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.

Why this matters

High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.

Source: web.dev

D
Third-Party Impact
Action
100% third-party, 0 ms blocking
FIX
100% third-party, 0 ms blocking
Warning::
Third-party code accounts for 100% of page weight (11.6 MiB of 11.6 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
D
JS Execution Cost
Action
3247ms total JS execution
FIX
3247ms total JS execution
Warning::
https://edition.cnn.com/: 1692ms CPU time
Warning::
Unattributable: 413ms CPU time
Warning::
https://registry.api.cnn.io/bundles/fave/boltPlaye...: 342ms CPU time
Info::
https://edition.cnn.com/media/sites/js/bundles/cnn...: 152ms CPU time
Info::
https://registry.api.cnn.io/bundles/fave/vendor-f9...: 136ms CPU time
Warning::
Third-party scripts: 3247ms (100% of total)

Main Thread Breakdown

Script Evaluation 33% Other 25% Style & Layout 18% Script Parsing & Compilation 12% Rendering 9% Parse HTML & CSS 4%
ScriptTotalScriptingParse/CompileParty
https://edition.cnn.com/1692ms205ms117ms3rd
Unattributable413ms12ms0ms3rd
https://registry.api.cnn.io/bundles/fave/boltPlayer-b296f72a/boltPlayer342ms261ms54ms3rd
https://edition.cnn.com/media/sites/js/bundles/cnn-edition-adfuel-275d6f33a8b3e59631886f14a6ce5dda2ec37648bb4b63d7ab13f3449be68c3d.min.js152ms124ms28ms3rd
https://registry.api.cnn.io/bundles/fave/vendor-f9ea2c98/vendor136ms76ms27ms3rd
https://registry.api.cnn.io/bundles/fave/boltInstance-476be30d/boltInstance122ms107ms7ms3rd
https://registry.api.cnn.io/bundles/fave/ui-34be6e59/ui100ms23ms78ms3rd
https://cdn.tinypass.com/api/tinypass.min.js86ms53ms9ms3rd
https://lightning.cnn.com/launch/7be62238e4c3/97fa00444124/launch-2878c87af5e3.min.js73ms43ms28ms3rd
https://registry.api.cnn.io/bundles/fave/latest-4.x/js65ms44ms19ms3rd

Showing top 10 of 11 scripts

F
JS Bundles
Action
33 scripts, 1.4 MB unused
FIX
33 scripts, 1.4 MB unused
Warning::
https://registry.api.cnn.io/bundles/fave/boltPlaye...: 321 KB unused (52%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://registry.api.cnn.io/bundles/fave/ui-34be6e...: 260 KB unused (11%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://registry.api.cnn.io/bundles/fave/vendor-f9...: 229 KB unused (69%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://edition.cnn.com/media/sites/js/bundles/cnn...: 160 KB unused (74%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.tinypass.com/api/tinypass.min.js: 83 KB unused (63%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 1.4 MB
1465 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://registry.api.cnn.io/bundles/fave/boltPlayer-b296f72a/boltPlayer618 KB321 KB (52%)✓3rd
https://registry.api.cnn.io/bundles/fave/ui-34be6e59/ui2310 KB260 KB (11%)✓3rd
https://registry.api.cnn.io/bundles/fave/vendor-f9ea2c98/vendor340 KB229 KB (69%)✓3rd
https://edition.cnn.com/media/sites/js/bundles/cnn-edition-adfuel-275d6f33a8b3e59631886f14a6ce5dda2ec37648bb4b63d7ab13f3449be68c3d.min.js216 KB160 KB (74%)✓3rd
https://cdn.tinypass.com/api/tinypass.min.js132 KB83 KB (63%)✓3rd
https://edition.cnn.com/wbdotp/scripttemplates/202601.2.0/otBannerSdk.js111 KB81 KB (74%)✓3rd
https://accounts.google.com/gsi/client94 KB69 KB (75%)✓3rd
https://cdn.optimizely.com/public/125375509/s/landingprod.js122 KB69 KB (57%)✓3rd
https://registry.api.cnn.io/bundles/fave/latest-4.x/js116 KB44 KB (38%)✓3rd
https://lightning.cnn.com/analytics/comscore/comscore-JS-7.13.1.min.js51 KB40 KB (78%)✓3rd

Consider code splitting or tree shaking to reduce unused code.

Why this matters

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.

Why this matters

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.

Why this matters

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.

Why this matters

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.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

B
Image Optimization
94 images, 0 KB saveable
REVIEW
94 images, 0 KB saveable
Info::
All images are well-optimized
94 images 3.5 MB
0 oversized -0 KB
18 legacy format
0 missing dimensions CLS risk
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Text Compression
All text resources are compressed
PASS
All text resources are compressed
Info::
All text resources are compressed
All text resources are properly compressed.
A+
Font Loading
5 fonts (221 KB)
PASS
5 fonts (221 KB)
Info::
5 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

5

221 KB total

Render-blocking

0

of 5

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s 1.5 s FCP 1.4 s LCP 1.9 shttps://edition.cnn.com/fonts/cnn/cnn_sans_display-v1.woff2cnn_sans_display-v1.woff2 https://edition.cnn.com/fonts/cnn/cnn_sans_display-v1.woff2 — 46.5 KiB — 0 ms — font-display: swaphttps://edition.cnn.com/fonts/cnn/cnn_sans_display-medium-v1.woff2cnn_sans_display-medium... https://edition.cnn.com/fonts/cnn/cnn_sans_display-medium-v1.woff2 — 46.4 KiB — 0 ms — font-display: swaphttps://edition.cnn.com/fonts/cnn/cnn_sans_display-bold-v1.woff2cnn_sans_display-bold-v... https://edition.cnn.com/fonts/cnn/cnn_sans_display-bold-v1.woff2 — 47.2 KiB — 0 ms — font-display: swaphttps://ix.cnn.io/static/fonts/latest/cnnsans-bold.woff2cnnsans-bold.woff2 https://ix.cnn.io/static/fonts/latest/cnnsans-bold.woff2 — 34.9 KiB — 0 ms — font-display: swaphttps://ix.cnn.io/static/fonts/latest/cnnsans-regular.woff2cnnsans-regular.woff2 https://ix.cnn.io/static/fonts/latest/cnnsans-regular.woff2 — 45.9 KiB — 0 ms — font-display: swap
cnn_sans_display-v1.woff2 woff2 swap
Size 46 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
cnn_sans_display-medium... woff2 swap
Size 46 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
cnn_sans_display-bold-v... woff2 swap
Size 47 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
cnnsans-bold.woff2 woff2 swap
Size 35 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
cnnsans-regular.woff2 woff2 swap
Size 46 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
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 Caching
All resources properly cached
PASS
All resources properly cached
Info::
No caching issues found
All static resources have appropriate caching headers.
A+
Critical Rendering Path
No render-blocking resources
PASS
No render-blocking resources
Info::
No render-blocking resources detected
A+
Resource Hints
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
A
HTTP Caching
max-age=60 (1 minute)
PASS
max-age=60 (1 minute)
Info::
Cache-Control header is set
Got: max-age=60, public
Info::
Effective TTL: 1 minute (max-age=60)
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

max-age=60, public

DirectiveValueMeaning
max-age60Cache for 1 minute
public—Any cache may store this response
Effective TTL: 60 seconds
Network Waterfall
179 requests over 0ms
INFO

Performance analysis not available for this result.

Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
100% of JavaScript execution is third-party
First-party Third-party 3247ms · 4429KB · $43/mo
edition.cnn.com
Other
Costly
Execution 1692ms
Transfer 504 KB
Monthly Cost $22/mo
Unattributable
Other
Costly
Execution 413ms
Transfer 0 KB
Monthly Cost $5/mo
registry.api.cnn.io
Other
Costly
Execution 342ms
Transfer 618 KB
Unused 52%
Monthly Cost $5/mo
edition.cnn.com
Other
Optional
Execution 152ms
Transfer 216 KB
Unused 74%
Monthly Cost $2/mo
registry.api.cnn.io
Other
Optional
Execution 136ms
Transfer 340 KB
Unused 69%
Monthly Cost $2/mo
registry.api.cnn.io
Other
Optional
Execution 122ms
Transfer 75 KB
Unused 50%
Monthly Cost $2/mo
registry.api.cnn.io
Other
Optional
Execution 100ms
Transfer 2310 KB
Unused 11%
Monthly Cost $1/mo
cdn.tinypass.com
Other
Optional
Execution 86ms
Transfer 132 KB
Unused 63%
Monthly Cost $1/mo
lightning.cnn.com
Other
Optional
Execution 73ms
Transfer 74 KB
Monthly Cost $1/mo
registry.api.cnn.io
Other
Optional
Execution 65ms
Transfer 116 KB
Unused 38%
Monthly Cost $1/mo
edition.cnn.com
Other
Optional
Execution 64ms
Transfer 44 KB
Unused 67%
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • edition.cnn.com adds 1692ms and costs ~$22/month
  • Unattributable adds 413ms and costs ~$5/month
  • registry.api.cnn.io adds 342ms and costs ~$5/month

100% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.

Why this matters

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

edition.cnn.com takes 1692ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

Unattributable takes 413ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

registry.api.cnn.io takes 342ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

52% of registry.api.cnn.io's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

74% of edition.cnn.com's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

69% of registry.api.cnn.io's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

63% of cdn.tinypass.com's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

67% of edition.cnn.com's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

How third-party costs are calculated

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

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