Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.

SCORE

GRADE

FIX

REVIEW

PASS

INFO

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

Mobile Desktop

Performance

Accessibility

Best Practices

SEO

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

3.25 s

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

5.04 s

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

900 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.

3.25 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.

5.46 s

Page Load Progression

433 ms

866 ms

1.3 s

1.7 s

2.2 s

2.6 s

3.0 s

3.5 s

Checks

12 PASS 1 REVIEW 2 FIX

Third-Party Impact

Action

100% third-party, 0 ms blocking

FIX

100% third-party, 0 ms blocking

Third-party code accounts for 100% of page weight (498.0 KiB of 498.6 KiB)

Third-party blocking time is low (0 ms)

100%

First-party Third-party

HTTP Caching

Action

no-store (uncacheable)

FIX

no-store (uncacheable)

Cache-Control: no-store prevents all caching

Intentional for dynamic content, but increases server load for every page view.

Got: private, max-age=0, no-store, no-cache, must-revalidate, post-check=0, pre-check=0

No ETag or Last-Modified header

Conditional requests (304 Not Modified) are not possible without validators.

Cache-Control

private, max-age=0, no-store, no-cache, must-revalidate, post-check=0, pre-check=0

Directive	Value	Meaning
private	—	Only browser cache, not CDN/proxy
max-age	0	Cache for 0 seconds
no-store	—	Never cache this response
no-cache	—	Cache but always revalidate first
must-revalidate	—	Must recheck with server after expiry
post-check	0
pre-check	0

JS Execution Cost

Action

1550ms total JS execution

REVIEW

1550ms total JS execution

https://www.pnas.org/cdn-cgi/challenge-platform/h/...: 1317ms CPU time

Unattributable: 138ms CPU time

https://www.pnas.org/: 95ms CPU time

Third-party scripts: 1550ms (100% of total)

Main Thread Breakdown

Script Evaluation 80% Other 11% Garbage Collection 3%

Script	Total	Scripting	Parse/Compile	Party
https://www.pnas.org/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=9efe9fffbab342c8	1317ms	1238ms	22ms	3rd
Unattributable	138ms	5ms	0ms	3rd
https://www.pnas.org/	95ms	12ms	2ms	3rd

A+

Page Weight Budget

499 KB transferred, 23 requests

PASS

499 KB transferred, 23 requests

Page weighs 890 KB (499 KB transferred)

23 HTTP requests

Estimated 0.10 g CO2 per page load

499 KB transferred

23 requests

0.10 g CO2 per page load

Other 305.3 KiB 61%

HTML 100.3 KiB 20%

JavaScript 86.7 KiB 17%

Other 3.3 KiB 1%

Other 1.7 KiB 0%

Images 1.3 KiB 0%

0 2.4 MB 4.9 MB

Under budget

A+

Text Compression

All text resources are compressed

PASS

All text resources are compressed

All text resources are properly compressed.

Image Optimization

3 images, 0 KB saveable

PASS

3 images, 0 KB saveable

All images are well-optimized

3 images 1 KB

0 oversized -0 KB

3 legacy format

0 missing dimensions CLS risk

A+

Font Loading

No web fonts (system fonts)

PASS

No web fonts (system fonts)

No web fonts loaded — system fonts are fastest

No web fonts loaded — system fonts are optimal.

A+

JS Bundles

7 scripts, 0 KB unused

PASS

7 scripts, 0 KB unused

0 KB unused JavaScript

Downloaded but never executed on this page.

Script	Size	Unused	Minified	Party
https://www.pnas.org/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=9efe9fffbab342c8	69 KB	—	✓	3rd
blob:https://www.pnas.org/aeb6b0a6-e3af-4c52-b21b-cd329f3f9752	0 KB	—	✓	3rd
https://challenges.cloudflare.com/turnstile/v0/b/0b8fb825cb67/api.js?onload=cFRiY3&render=explicit	17 KB	—	✓	3rd
blob:https://www.pnas.org/22ccbb39-1ab7-4c8e-bee0-fb6d1eead00d	-0 KB	—	✓	3rd
blob:https://challenges.cloudflare.com/30534622-8a02-4a6c-bc2d-371c227c6e2b	0 KB	—	✓	3rd
blob:https://challenges.cloudflare.com/22e45859-f0bc-40d7-80e7-63cad3da5d3a	-0 KB	—	✓	3rd
blob:https://challenges.cloudflare.com/22e45859-f0bc-40d7-80e7-63cad3da5d3a	-0 KB	—	✓	3rd

A+

Resource Caching

All resources properly cached

PASS

All resources properly cached

No caching issues found

All static resources have appropriate caching headers.

A+

Critical Rendering Path

No render-blocking resources

PASS

No render-blocking resources

No render-blocking resources detected

A+

Resource Hints

No optimization needed

PASS

No optimization needed

No resource hint issues

Page Weight Inventory

23 resources · 499 KB · 0 KB savings available

PASS

23 resources · 499 KB · 0 KB savings available

Within 1MB page-weight target

Got: 499 KB

21 third-party resources (100% of weight)

1 resources over 200KB

23 resources · 498.6 KiB · 21 third-party Within 1MB page-weight target

Other 62% · 310.0 KiB

Document 20% · 100.3 KiB

JavaScript 17% · 86.7 KiB

Image 0% · 1.7 KiB

#	Resource	Type	Size	Cache	Unused	3rd party	Issues

23 resources			498.6 KiB

A+

Render-Blocking Resources

No render-blocking resources detected

PASS

No render-blocking resources detected

No render-blocking resources detected in <head>

A+

Third-Party Resources

No third-party resources detected

PASS

No third-party resources detected

A+

Green Hosting

Whether the site is served from green-energy infrastructure

PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Cloudflare

Network Waterfall

23 requests over 3219ms

INFO

HTML JavaScript CSS Images Fonts XHR/Fetch Other

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 1550ms · 74KB · $21/mo

Script	Category	Execution	Transfer	Unused	Monthly Cost	Verdict
www.pnas.org www.pnas.org	Other	1317ms	69 KB	—	$17/mo	Costly
Unattributable Unattributable	Other	138ms	0 KB	—	$2/mo	Optional
www.pnas.org www.pnas.org	Other	95ms	5 KB	—	$1/mo	Optional

www.pnas.org

Other

Costly

Execution 1317ms

Transfer 69 KB

Monthly Cost $17/mo

Unattributable

Other

Optional

Execution 138ms

Transfer 0 KB

Monthly Cost $2/mo

www.pnas.org

Other

Optional

Execution 95ms

Transfer 5 KB

Monthly Cost $1/mo

These scripts may cost more than they're worth

www.pnas.org adds 1317ms and costs ~$17/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

www.pnas.org takes 1317ms 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.