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Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
73
GRADE
C
FIX
5
REVIEW
2
PASS
5
INFO
2

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

Mobile Desktop
41
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
97
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
100
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
100
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.

2.66 s

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

9.50 s

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

2.42 s

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.

3.92 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.

12.83 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
14
5 PASS 2 REVIEW 5 FIX
D
Page Weight Budget
Action
2.1 MB transferred, 47 requests
FIX
2.1 MB transferred, 47 requests
Info::
Page weighs 7.1 MB (2.1 MB transferred)
Warning::
JavaScript is 951 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 951 KB
Info::
47 HTTP requests
Info::
Estimated 0.43 g CO2 per page load
2.1 MB / 2.4 MB budget
2.1 MB transferred
47 requests
0.43 g CO2 per page load
JavaScript 951.3 KiB 45%
Images 804.6 KiB 38%
Other 159.4 KiB 8%
Fonts 112.2 KiB 5%
HTML 38.8 KiB 2%
CSS 28.9 KiB 1%
Other 26.0 KiB 1%
Other 0 B 0%
0 2.4 MB 4.9 MB
Approaching limit

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

D
Third-Party Impact
Action
97% third-party, 0 ms blocking
FIX
97% third-party, 0 ms blocking
Warning::
Third-party code accounts for 97% of page weight (2.0 MiB of 2.1 MiB)
Info::
Third-party blocking time is low (0 ms)
97%
First-party Third-party
F
JS Execution Cost
Action
5935ms total JS execution
FIX
5935ms total JS execution
Warning::
https://arstechnica.com/: 1295ms CPU time
Warning::
https://privacy.condenastdigital.com/fides.js?prop...: 970ms CPU time
Warning::
https://cdn.arstechnica.net/wp-content/themes/ars-...: 954ms CPU time
Warning::
Unattributable: 785ms CPU time
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-NLX...: 606ms CPU time
Warning::
Third-party scripts: 4521ms (76% of total)

Main Thread Breakdown

Script Evaluation 49% Other 16% Style & Layout 15% Script Parsing & Compilation 13% Parse HTML & CSS 4%
ScriptTotalScriptingParse/CompileParty
https://arstechnica.com/1295ms86ms24ms1st
https://privacy.condenastdigital.com/fides.js?property_id=FDS-MIKT8M&970ms570ms335ms3rd
https://cdn.arstechnica.net/wp-content/themes/ars-v9/public/js/app.25ba18.js954ms788ms35ms3rd
Unattributable785ms24ms0ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-NLXNPCQ606ms489ms104ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-PVBXQMCR&gtm=4e6411360ms235ms69ms3rd
https://securepubads.g.doubleclick.net/pagead/managed/js/gpt/m202603310101/pubads_impl.js325ms228ms94ms3rd
https://www.googletagservices.com/tag/js/gpt.js143ms125ms17ms3rd
https://globalservices.conde.digital/p77xzrbz9z.js142ms119ms16ms3rd
https://planebasin.com/dist/25dd01b14_8715a062a12be6f05714ee41f1a252e6e86d0.index.js137ms106ms12ms3rd

Showing top 10 of 12 scripts

D
JS Bundles
Action
16 scripts, 390 KB unused
FIX
16 scripts, 390 KB unused
Warning::
https://securepubads.g.doubleclick.net/pagead/mana...: 140 KB unused (77%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-NLX...: 76 KB unused (44%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-PVB...: 59 KB unused (50%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.arstechnica.net/wp-content/themes/ars-...: 58 KB unused (82%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://ads-static.conde.digital/production/cns/bu...: 32 KB unused (80%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 390 KB
390 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://securepubads.g.doubleclick.net/pagead/managed/js/gpt/m202603310101/pubads_impl.js182 KB140 KB (77%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-NLXNPCQ173 KB76 KB (44%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-PVBXQMCR&gtm=4e6411118 KB59 KB (50%)✓3rd
https://cdn.arstechnica.net/wp-content/themes/ars-v9/public/js/app.25ba18.js71 KB58 KB (82%)✓3rd
https://ads-static.conde.digital/production/cns/builds/ars-technica/ars-technica.min.js41 KB32 KB (80%)✓3rd
https://cdn.arstechnica.net/wp/wp-includes/js/jquery/jquery.min.js?ver=3.7.134 KB24 KB (73%)✓3rd
https://arstechnica.com/wp-content/themes/ars-v9/public/js/cntracking.8e5b8b.js32 KB—✓1st
https://cdn.arstechnica.net/wp-content/plugins/article-forum-connect/public/js/iframe.js?ver=1.2.42 KB—✓3rd
https://cdn.arstechnica.net/wp-content/themes/ars-v9/public/js/stats.74db3c.js4 KB—✓3rd
https://cdn.arstechnica.net/wp-content/plugins/article-forum-connect/public/js/iframe-resizer.parent.js?ver=5.3.18 KB—✓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

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.

B
Image Optimization
14 images, 0 KB saveable
REVIEW
14 images, 0 KB saveable
Warning::
https://cdn.arstechnica.net/wp-content/uploads/202... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
14 images 805 KB
0 oversized -0 KB
14 legacy format
1 missing dimensions CLS risk

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

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
4 fonts (112 KB)
PASS
4 fonts (112 KB)
Info::
4 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

4

112 KB total

Render-blocking

0

of 4

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s 7.0 s 8.0 s 9.0 s FCP 2.7 s LCP 9.5 shttps://cdn.arstechnica.net/wp-content/themes/ars-v9/public/fonts/nwpStKy2OAdR1K-IwhWudF-R3w8aZQ.bf9a29.woff2nwpStKy2OAdR1K-IwhWudF-... https://cdn.arstechnica.net/wp-content/themes/ars-v9/public/fonts/nwpStKy2OAdR1K-IwhWudF-R3w8aZQ.bf9a29.woff2 — 24.7 KiB — 0 ms — font-display: swaphttps://cdn.arstechnica.net/wp-content/themes/ars-v9/public/fonts/7cHmv4okm5zmbtYoK-4.a71c5e.woff27cHmv4okm5zmbtYoK-4.a71... https://cdn.arstechnica.net/wp-content/themes/ars-v9/public/fonts/7cHmv4okm5zmbtYoK-4.a71c5e.woff2 — 39.2 KiB — 0 ms — font-display: swaphttps://cdn.arstechnica.net/wp-content/themes/ars-v9/public/fonts/XLYlIZPxYpJfTbZAFV-_Hcw.6df07f.woff2XLYlIZPxYpJfTbZAFV-_Hcw... https://cdn.arstechnica.net/wp-content/themes/ars-v9/public/fonts/XLYlIZPxYpJfTbZAFV-_Hcw.6df07f.woff2 — 24.0 KiB — 0 ms — font-display: swaphttps://cdn.arstechnica.net/wp-content/themes/ars-v9/public/fonts/nwpMtKy2OAdR1K-IwhWudF-R3woqZ-LY.802cca.woff2nwpMtKy2OAdR1K-IwhWudF-... https://cdn.arstechnica.net/wp-content/themes/ars-v9/public/fonts/nwpMtKy2OAdR1K-IwhWudF-R3woqZ-LY.802cca.woff2 — 24.4 KiB — 0 ms — font-display: swap
nwpStKy2OAdR1K-IwhWudF-... woff2 swap
Size 25 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
7cHmv4okm5zmbtYoK-4.a71... woff2 swap
Size 39 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
XLYlIZPxYpJfTbZAFV-_Hcw... woff2 swap
Size 24 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
nwpMtKy2OAdR1K-IwhWudF-... woff2 swap
Size 24 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
3 hints, 0 missing preconnects
PASS
3 hints, 0 missing preconnects
Info::
Page uses 3 resource hint(s)

Current Resource Hints

preconnect
3
preload
—
dns-prefetch
—
prefetch
—

3 resource hints configured

Network Waterfall
47 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
76% of JavaScript execution is third-party
First-party Third-party 4521ms · 862KB · €49/mo
privacy.condenastdigital.com
Other
Costly
Execution 970ms
Transfer 198 KB
Monthly Cost €11/mo
cdn.arstechnica.net
Other
Costly
Execution 954ms
Transfer 71 KB
Unused 82%
Monthly Cost €10/mo
Unattributable
Other
Costly
Execution 785ms
Transfer 0 KB
Monthly Cost €9/mo
Google Tag Manager
Tag Manager
Costly
Execution 606ms
Transfer 173 KB
Unused 44%
Monthly Cost €7/mo
Google Tag Manager
Tag Manager
Costly
Execution 360ms
Transfer 118 KB
Unused 50%
Monthly Cost €4/mo
securepubads.g.doubleclick.net
Other
Costly
Execution 325ms
Transfer 182 KB
Unused 77%
Monthly Cost €4/mo
www.googletagservices.com
Other
Optional
Execution 143ms
Transfer 34 KB
Monthly Cost €2/mo
globalservices.conde.digital
Other
Optional
Execution 142ms
Transfer 26 KB
Monthly Cost €2/mo
planebasin.com
Other
Optional
Execution 137ms
Transfer 25 KB
Monthly Cost €1/mo
cdn.arstechnica.net
Other
Optional
Execution 98ms
Transfer 34 KB
Unused 73%
Monthly Cost €1/mo

These scripts may cost more than they're worth

  • privacy.condenastdigital.com adds 970ms and costs ~€11/month
  • cdn.arstechnica.net adds 954ms and costs ~€10/month
  • Unattributable adds 785ms and costs ~€9/month
  • Google Tag Manager adds 606ms and costs ~€7/month
  • Google Tag Manager adds 360ms and costs ~€4/month
  • securepubads.g.doubleclick.net adds 325ms and costs ~€4/month

76% 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

privacy.condenastdigital.com takes 970ms 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

cdn.arstechnica.net takes 954ms 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

82% of cdn.arstechnica.net'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 785ms 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

Google Tag Manager takes 606ms 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

Google Tag Manager takes 360ms 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

50% of Google Tag Manager'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

securepubads.g.doubleclick.net takes 325ms 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

77% of securepubads.g.doubleclick.net'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

73% of cdn.arstechnica.net'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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