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https://c-span.org

Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
88
GRADE
B
FIX
2
REVIEW
4
PASS
9
INFO
2

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

Mobile Desktop
72
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
73
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
88
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
80
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.

4.64 s

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

4.64 s

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

0 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.

4.64 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.

4.64 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 s
Checks
17
9 PASS 4 REVIEW 2 FIX
D
Third-Party Impact
Action
99% third-party, 0 ms blocking
FIX
99% third-party, 0 ms blocking
Warning::
Third-party code accounts for 99% of page weight (503.4 KiB of 507.6 KiB)
Info::
Third-party blocking time is low (0 ms)
99%
First-party Third-party
F
HTTP Caching
Action
No cache headers
FIX
No cache headers
Warning::
No Cache-Control header found
Browsers will use heuristic caching, which can be unpredictable. Set explicit cache headers.

No Cache-Control header

Adding a Cache-Control header can significantly improve repeat-visit performance.

C
JS Execution Cost
Action
1018ms total JS execution
REVIEW
1018ms total JS execution
Warning::
https://6641b4a4704d.45ee037c.eu-west-3.token.awsw...: 751ms CPU time
Info::
Unattributable: 210ms CPU time
Info::
https://c-span.org/: 57ms CPU time
Warning::
Third-party scripts: 961ms (94% of total)

Main Thread Breakdown

Script Evaluation 65% Script Parsing & Compilation 17% Other 16%
ScriptTotalScriptingParse/CompileParty
https://6641b4a4704d.45ee037c.eu-west-3.token.awswaf.com/6641b4a4704d/5045973e9650/f6c5d1196928/challenge.js751ms520ms176ms3rd
Unattributable210ms105ms0ms3rd
https://c-span.org/57ms33ms1ms1st
C
JS Bundles
Action
1 scripts, 278 KB unused
REVIEW
1 scripts, 278 KB unused
Warning::
https://6641b4a4704d.45ee037c.eu-west-3.token.awsw...: 278 KB unused (55%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 278 KB
278 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://6641b4a4704d.45ee037c.eu-west-3.token.awswaf.com/6641b4a4704d/5045973e9650/f6c5d1196928/challenge.js501 KB278 KB (55%)✓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

B
Page Weight Inventory
8 resources · 508 KB · 278 KB savings available
REVIEW
8 resources · 508 KB · 278 KB savings available
Info::
Within 1MB page-weight target
Got: 508 KB
Info::
~278 KB of savings available
Warning::
4 third-party resources (99% of weight)
Info::
1 resources over 200KB
8 resources · 507.6 KiB · 4 third-party Within 1MB page-weight target
JavaScript 99% · 501.4 KiB
Document 1% · 4.1 KiB
Other 0% · 2.0 KiB

~277.7 KiB of savings available

Remove unused JavaScript: 277.7 KiB
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Page Weight Budget
508 KB transferred, 8 requests
PASS
508 KB transferred, 8 requests
Info::
Page weighs 1.3 MB (508 KB transferred)
Warning::
JavaScript is 501 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 501 KB
Info::
8 HTTP requests
Info::
Estimated 0.10 g CO2 per page load
508 KB / 2.4 MB budget
508 KB transferred
8 requests
0.10 g CO2 per page load
JavaScript 501.4 KiB 99%
HTML 3.3 KiB 1%
Other 2.0 KiB 0%
Other 911 B 0%
0 2.4 MB 4.9 MB
Under 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

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+
Image Optimization
No images on this page
PASS
No images on this page
Info::
No images on this page
0 images 0 KB
0 oversized -0 KB
0 legacy format
0 missing dimensions CLS risk
A+
Font Loading
No web fonts (system fonts)
PASS
No web fonts (system fonts)
Info::
No web fonts loaded — system fonts are fastest
No web fonts loaded — system fonts are optimal.
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+
Render-Blocking Resources
No render-blocking resources detected
PASS
No render-blocking resources detected
Info::
No render-blocking resources detected in <head>
A+
Third-Party Resources
No third-party resources detected
PASS
No third-party resources detected
Network Waterfall
8 requests over 665ms
INFO
0 ms 1.0 s 2.0 s 3.0 s 4.0 s FCP 4.6 s LCP 4.6 shttps://c-span.org// https://c-span.org/ — 202 — 2.8 KiB — 65 ms — h2https://6641b4a4704d.45ee037c.eu-west-3.token.awswaf.com/6641b4a4704d/5045973e9650/f6c5d1196928/challenge.js6641b4a4704d.45ee037c.eu-west-3.tok... https://6641b4a4704d.45ee037c.eu-west-3.token.awswaf.com/6641b4a4704d/5045973e9650/f6c5d1196928/challenge.js — 200 — 501.4 KiB — 174 ms — h2https://6641b4a4704d.45ee037c.eu-west-3.token.awswaf.com/6641b4a4704d/5045973e9650/f6c5d1196928/inputs?client=browser6641b4a4704d.45ee037c.eu-west-3.tok... https://6641b4a4704d.45ee037c.eu-west-3.token.awswaf.com/6641b4a4704d/5045973e9650/f6c5d1196928/inputs?client=browser — 200 — 826 B — 55 ms — h3https://c-span.org/favicon.ico/favicon.ico https://c-span.org/favicon.ico — 403 — 484 B — 23 ms — h2https://6641b4a4704d.45ee037c.eu-west-3.token.awswaf.com/6641b4a4704d/5045973e9650/f6c5d1196928/mp_verify6641b4a4704d.45ee037c.eu-west-3.tok... https://6641b4a4704d.45ee037c.eu-west-3.token.awswaf.com/6641b4a4704d/5045973e9650/f6c5d1196928/mp_verify — 200 — 624 B — 73 ms — h3https://6641b4a4704d.45ee037c.eu-west-3.token.awswaf.com/6641b4a4704d/5045973e9650/f6c5d1196928/mp_verify6641b4a4704d.45ee037c.eu-west-3.tok... https://6641b4a4704d.45ee037c.eu-west-3.token.awswaf.com/6641b4a4704d/5045973e9650/f6c5d1196928/mp_verify — 200 — 626 B — 54 ms — h3https://c-span.org// https://c-span.org/ — 403 — 427 B — 24 ms — h3https://c-span.org/favicon.ico/favicon.ico https://c-span.org/favicon.ico — 403 — 427 B — 24 ms — h3
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
94% of JavaScript execution is third-party
First-party Third-party 961ms · 501KB · $13/mo
6641b4a4704d.45ee037c.eu-west-3.token.awswaf.com
Other
Costly
Execution 751ms
Transfer 501 KB
Unused 55%
Monthly Cost $10/mo
Unattributable
Other
Costly
Execution 210ms
Transfer 0 KB
Monthly Cost $3/mo

These scripts may cost more than they're worth

  • 6641b4a4704d.45ee037c.eu-west-3.token.awswaf.com adds 751ms and costs ~$10/month
  • Unattributable adds 210ms and costs ~$3/month

94% 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

6641b4a4704d.45ee037c.eu-west-3.token.awswaf.com takes 751ms 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

55% of 6641b4a4704d.45ee037c.eu-west-3.token.awswaf.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

Unattributable takes 210ms 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

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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