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Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
79
GRADE
C
FIX
4
REVIEW
3
PASS
6
INFO
2

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

Mobile Desktop
67
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
89
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
96
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.

2.22 s

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

3.73 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.

0.001

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

2.22 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.

3.73 s

Page Load Progression

377 ms
754 ms
1.1 s
1.5 s
1.9 s
2.3 s
2.6 s
3.0 s
Checks
15
6 PASS 3 REVIEW 4 FIX
F
Page Weight Budget
Action
3.1 MB transferred, 53 requests
FIX
3.1 MB transferred, 53 requests
Warning::
Page weighs 3.1 MB (3.1 MB transferred)
Info::
CSS is 1.2 MB — consider purging unused styles
Remove unused CSS rules with tools like PurgeCSS to reduce stylesheet size.
Got: 1.2 MB
Info::
Fonts are 718 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 718 KB
Info::
53 HTTP requests
Info::
Estimated 0.65 g CO2 per page load
3.1 MB / 2.4 MB budget
3.1 MB transferred
53 requests
0.65 g CO2 per page load
CSS 1.2 MiB 38%
Images 826.4 KiB 26%
Fonts 717.7 KiB 23%
JavaScript 283.9 KiB 9%
HTML 93.6 KiB 3%
Other 19.0 KiB 1%
Other 4.6 KiB 0%
0 2.4 MB 4.9 MB
Over budget

Remove unused CSS rules with tools like PurgeCSS to reduce stylesheet size.

Why this matters

CSS bundle is large — purge unused styles (PurgeCSS, Tailwind JIT) to reduce CSS payload.

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

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 (3.1 MiB of 3.1 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
D
Page Weight Inventory
Action
53 resources · 3.1 MB · 63 KB savings available
FIX
53 resources · 3.1 MB · 63 KB savings available
Warning::
Page weight 2.1 MB over 1MB target
Got: 3.1 MB Expected: ≤ 1 MB
Info::
~63 KB of savings available
Warning::
52 third-party resources (100% of weight)
Info::
5 resources over 200KB
53 resources · 3.1 MiB · 52 third-party 2.1 MiB over 1MB target
CSS 38% · 1.2 MiB
Image 27% · 844.3 KiB
Font 23% · 717.7 KiB
JavaScript 9% · 283.9 KiB
Document 3% · 93.6 KiB
Other 0% · 5.7 KiB

~63.0 KiB of savings available

Remove unused JavaScript: 63.0 KiB
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
Image Optimization
Action
9 images, 0 KB saveable
REVIEW
9 images, 0 KB saveable
Warning::
https://developer.apple.com/assets/elements/icons/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://developer.apple.com/assets/elements/icons/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
9 images 826 KB
0 oversized -0 KB
8 legacy format
2 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

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

B
JS Bundles
15 scripts, 63 KB unused
REVIEW
15 scripts, 63 KB unused
Warning::
https://developer.apple.com/assets/scripts/lib/jqu...: 63 KB unused (72%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://developer.apple.com/assets/metrics/scripts...: unminified — 3 KB could be saved
Info::
Total unused JavaScript: 63 KB
63 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://developer.apple.com/assets/scripts/lib/jquery/jquery-3.6.0.min.js?4523260803089 KB63 KB (72%)✓3rd
https://developer.apple.com/assets/scripts/settings.js?452326080302 KB—✓3rd
https://developer.apple.com/assets/scripts/language-locales.js?452326080302 KB—✓3rd
https://developer.apple.com/assets/scripts/DeveloperBreadcrumbs.js?452326080306 KB—✓3rd
https://developer.apple.com/assets/metrics/scripts/analytics-module.js?452326080306 KB—✗3rd
https://developer.apple.com/assets/scripts/global-logout.js?452326080302 KB—✓3rd
https://developer.apple.com/assets/scripts/suggest-lang.js?031626260575 KB—✓3rd
https://developer.apple.com/assets/scripts/ac-globalnav.built.js?0117263805716 KB—✓3rd
https://developer.apple.com/assets/metrics/scripts/analytics.js83 KB—✗3rd
https://developer.apple.com/assets/scripts/ac-localnav.built.js52 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

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+
JS Execution Cost
369ms total JS execution
PASS
369ms total JS execution
Info::
https://developer.apple.com/icloud/: 218ms CPU time
Info::
Unattributable: 77ms CPU time
Info::
https://developer.apple.com/assets/scripts/ac-loca...: 74ms CPU time
Warning::
Third-party scripts: 369ms (100% of total)

Main Thread Breakdown

Other 41% Style & Layout 34% Script Evaluation 12% Rendering 6% Parse HTML & CSS 5%
ScriptTotalScriptingParse/CompileParty
https://developer.apple.com/icloud/218ms11ms1ms3rd
Unattributable77ms1ms0ms3rd
https://developer.apple.com/assets/scripts/ac-localnav.built.js74ms10ms1ms3rd
A+
Font Loading
6 fonts (718 KB)
PASS
6 fonts (718 KB)
Info::
6 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

6

718 KB total

Render-blocking

0

of 6

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 FCP 2.2 s LCP 3.7 shttps://www.apple.com/wss/fonts/SF-Pro-Text/v3/sf-pro-text_regular.woff2sf-pro-text_regular.woff2 https://www.apple.com/wss/fonts/SF-Pro-Text/v3/sf-pro-text_regular.woff2 — 216.2 KiB — 14 ms — font-display: swaphttps://www.apple.com/wss/fonts/SF-Pro-Display/v3/sf-pro-display_semibold.woff2sf-pro-display_semibold... https://www.apple.com/wss/fonts/SF-Pro-Display/v3/sf-pro-display_semibold.woff2 — 127.2 KiB — 22 ms — font-display: swaphttps://www.apple.com/wss/fonts/SF-Pro-Text/v3/sf-pro-text_semibold.woff2sf-pro-text_semibold.woff2 https://www.apple.com/wss/fonts/SF-Pro-Text/v3/sf-pro-text_semibold.woff2 — 229.6 KiB — 19 ms — font-display: swaphttps://www.apple.com/wss/fonts/SF-Pro-Icons/v3/sf-pro-icons_regular.woff2sf-pro-icons_regular.woff2 https://www.apple.com/wss/fonts/SF-Pro-Icons/v3/sf-pro-icons_regular.woff2 — 14.6 KiB — 6 ms — font-display: swaphttps://www.apple.com/wss/fonts/SF-Pro-Display/v3/sf-pro-display_regular.woff2sf-pro-display_regular.... https://www.apple.com/wss/fonts/SF-Pro-Display/v3/sf-pro-display_regular.woff2 — 115.1 KiB — 8 ms — font-display: swaphttps://www.apple.com/wss/fonts/SF-Pro-Icons/v3/sf-pro-icons_semibold.woff2sf-pro-icons_semibold.w... https://www.apple.com/wss/fonts/SF-Pro-Icons/v3/sf-pro-icons_semibold.woff2 — 15.0 KiB — 4 ms — font-display: swap
sf-pro-text_regular.woff2 woff2 swap
Size 216 KB
Load time 14 ms
Start 510 ms
Risk FOUT — text flashes from fallback to web font
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
sf-pro-display_semibold... woff2 swap
Size 127 KB
Load time 22 ms
Start 510 ms
Risk FOUT — text flashes from fallback to web font
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
sf-pro-text_semibold.woff2 woff2 swap
Size 230 KB
Load time 19 ms
Start 511 ms
Risk FOUT — text flashes from fallback to web font
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
sf-pro-icons_regular.woff2 woff2 swap
Size 15 KB
Load time 6 ms
Start 640 ms
Risk FOUT — text flashes from fallback to web font
sf-pro-display_regular.... woff2 swap
Size 115 KB
Load time 8 ms
Start 640 ms
Risk FOUT — text flashes from fallback to web font
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
sf-pro-icons_semibold.w... woff2 swap
Size 15 KB
Load time 4 ms
Start 660 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)

Fixing the unchecked items could save ~344 KB and ~688 ms

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
Network Waterfall
53 requests over 1196ms
INFO
0 ms 1.0 s 2.0 s 3.0 s FCP 2.2 s LCP 3.7 shttps://icloud-content.com// https://icloud-content.com/ — 301 — 191 B — 319 ms — http/1.1https://developer.apple.com/icloud/developer.apple.com/icloud/ https://developer.apple.com/icloud/ — 200 — 93.6 KiB — 42 ms — http/1.1https://developer.apple.com/assets/styles/global.dist.css?51172657083developer.apple.com/assets/styles/g... https://developer.apple.com/assets/styles/global.dist.css?51172657083 — 200 — 928.4 KiB — 52 ms — http/1.1https://sf-saas.cdn-apple.com/2.4.0-beta.0/animations/all.csssf-saas.cdn-apple.com/2.4.0-beta.0/... https://sf-saas.cdn-apple.com/2.4.0-beta.0/animations/all.css — -1 — 0 B — 30 ms — https://developer.apple.com/assets/styles/localization.css?54232608030developer.apple.com/assets/styles/l... https://developer.apple.com/assets/styles/localization.css?54232608030 — 200 — 18.4 KiB — 18 ms — http/1.1https://developer.apple.com/assets/scripts/lib/jquery/jquery-3.6.0.min.js?45232608030developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/lib/jquery/jquery-3.6.0.min.js?45232608030 — 200 — 88.7 KiB — 40 ms — http/1.1https://developer.apple.com/assets/scripts/settings.js?45232608030developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/settings.js?45232608030 — 200 — 2.0 KiB — 29 ms — http/1.1https://developer.apple.com/assets/scripts/language-locales.js?45232608030developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/language-locales.js?45232608030 — 200 — 2.1 KiB — 28 ms — http/1.1https://developer.apple.com/assets/scripts/DeveloperBreadcrumbs.js?45232608030developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/DeveloperBreadcrumbs.js?45232608030 — 200 — 5.6 KiB — 39 ms — http/1.1https://developer.apple.com/assets/metrics/scripts/analytics-module.js?45232608030developer.apple.com/assets/metrics/... https://developer.apple.com/assets/metrics/scripts/analytics-module.js?45232608030 — 200 — 5.9 KiB — 40 ms — http/1.1https://developer.apple.com/assets/scripts/global-logout.js?45232608030developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/global-logout.js?45232608030 — 200 — 2.2 KiB — 46 ms — http/1.1https://www.apple.com/wss/fonts?families=SF+Pro,v3|SF+Pro+Icons,v3www.apple.com/wss/fonts?families=SF... https://www.apple.com/wss/fonts?families=SF+Pro,v3|SF+Pro+Icons,v3 — 200 — 1.9 KiB — 31 ms — h2https://www.apple.com/wss/fonts?family=SF+Mono&v=2www.apple.com/wss/fonts?family=SF+M... https://www.apple.com/wss/fonts?family=SF+Mono&v=2 — 200 — 1.2 KiB — 29 ms — h2https://www.apple.com/wss/fonts?family=Apple+Icons&v=1www.apple.com/wss/fonts?family=Appl... https://www.apple.com/wss/fonts?family=Apple+Icons&v=1 — 200 — 1.1 KiB — 29 ms — h2https://developer.apple.com/icloud/styles/icloud-common.cssdeveloper.apple.com/icloud/styles/i... https://developer.apple.com/icloud/styles/icloud-common.css — 200 — 3.0 KiB — 11 ms — http/1.1https://developer.apple.com/assets/styles/suggest-lang.css?54232608030developer.apple.com/assets/styles/s... https://developer.apple.com/assets/styles/suggest-lang.css?54232608030 — 200 — 4.1 KiB — 19 ms — http/1.1https://developer.apple.com/assets/scripts/suggest-lang.js?03162626057developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/suggest-lang.js?03162626057 — 200 — 4.6 KiB — 38 ms — http/1.1https://developer.apple.com/assets/styles/globalnav.css?48212635068developer.apple.com/assets/styles/g... https://developer.apple.com/assets/styles/globalnav.css?48212635068 — 200 — 122.4 KiB — 21 ms — http/1.1https://developer.apple.com/assets/scripts/ac-globalnav.built.js?01172638057developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/ac-globalnav.built.js?01172638057 — 200 — 15.7 KiB — 41 ms — http/1.1https://developer.apple.com/assets/metrics/scripts/analytics.jsdeveloper.apple.com/assets/metrics/... https://developer.apple.com/assets/metrics/scripts/analytics.js — 200 — 83.1 KiB — 44 ms — http/1.1https://developer.apple.com/assets/styles/localnav.cssdeveloper.apple.com/assets/styles/l... https://developer.apple.com/assets/styles/localnav.css — 200 — 59.7 KiB — 20 ms — http/1.1https://developer.apple.com/assets/scripts/ac-localnav.built.jsdeveloper.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/ac-localnav.built.js — 200 — 51.6 KiB — 44 ms — http/1.1https://developer.apple.com/assets/scripts/localnav.jsdeveloper.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/localnav.js — 200 — 2.0 KiB — 43 ms — http/1.1https://developer.apple.com/assets/elements/icons/icloud/icloud-96x96_2x.pngdeveloper.apple.com/assets/elements... https://developer.apple.com/assets/elements/icons/icloud/icloud-96x96_2x.png — 200 — 14.7 KiB — 5 ms — http/1.1https://developer.apple.com/icloud/images/screen-hero-large_2x.png?1developer.apple.com/icloud/images/s... https://developer.apple.com/icloud/images/screen-hero-large_2x.png?1 — 200 — 355.1 KiB — 194 ms — http/1.1https://developer.apple.com/assets/elements/icons/xcode-s/xcode-s-96x96_2x.pngdeveloper.apple.com/assets/elements... https://developer.apple.com/assets/elements/icons/xcode-s/xcode-s-96x96_2x.png — 200 — 30.4 KiB — 5 ms — http/1.1https://developer.apple.com/assets/styles/footer.dist.css?54232608030developer.apple.com/assets/styles/f... https://developer.apple.com/assets/styles/footer.dist.css?54232608030 — 200 — 27.9 KiB — 3 ms — http/1.1https://developer.apple.com/assets/styles/language-dropdown.css?54232608030developer.apple.com/assets/styles/l... https://developer.apple.com/assets/styles/language-dropdown.css?54232608030 — 200 — 2.6 KiB — 3 ms — http/1.1https://developer.apple.com/assets/scripts/language-dropdown.js?45232608030developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/language-dropdown.js?45232608030 — 200 — 3.5 KiB — 8 ms — http/1.1https://developer.apple.com/assets/scripts/retinate.js?45232608030developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/retinate.js?45232608030 — 200 — 4.5 KiB — 8 ms — http/1.1
0 ms 1.0 s 2.0 s 3.0 s FCP 2.2 s LCP 3.7 shttps://icloud-content.com// https://icloud-content.com/ — 301 — 191 B — 319 ms — http/1.1https://developer.apple.com/icloud/developer.apple.com/icloud/ https://developer.apple.com/icloud/ — 200 — 93.6 KiB — 42 ms — http/1.1https://developer.apple.com/assets/styles/global.dist.css?51172657083developer.apple.com/assets/styles/g... https://developer.apple.com/assets/styles/global.dist.css?51172657083 — 200 — 928.4 KiB — 52 ms — http/1.1https://sf-saas.cdn-apple.com/2.4.0-beta.0/animations/all.csssf-saas.cdn-apple.com/2.4.0-beta.0/... https://sf-saas.cdn-apple.com/2.4.0-beta.0/animations/all.css — -1 — 0 B — 30 ms — https://developer.apple.com/assets/styles/localization.css?54232608030developer.apple.com/assets/styles/l... https://developer.apple.com/assets/styles/localization.css?54232608030 — 200 — 18.4 KiB — 18 ms — http/1.1https://developer.apple.com/assets/scripts/lib/jquery/jquery-3.6.0.min.js?45232608030developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/lib/jquery/jquery-3.6.0.min.js?45232608030 — 200 — 88.7 KiB — 40 ms — http/1.1https://developer.apple.com/assets/scripts/settings.js?45232608030developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/settings.js?45232608030 — 200 — 2.0 KiB — 29 ms — http/1.1https://developer.apple.com/assets/scripts/language-locales.js?45232608030developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/language-locales.js?45232608030 — 200 — 2.1 KiB — 28 ms — http/1.1https://developer.apple.com/assets/scripts/DeveloperBreadcrumbs.js?45232608030developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/DeveloperBreadcrumbs.js?45232608030 — 200 — 5.6 KiB — 39 ms — http/1.1https://developer.apple.com/assets/metrics/scripts/analytics-module.js?45232608030developer.apple.com/assets/metrics/... https://developer.apple.com/assets/metrics/scripts/analytics-module.js?45232608030 — 200 — 5.9 KiB — 40 ms — http/1.1https://developer.apple.com/assets/scripts/global-logout.js?45232608030developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/global-logout.js?45232608030 — 200 — 2.2 KiB — 46 ms — http/1.1https://www.apple.com/wss/fonts?families=SF+Pro,v3|SF+Pro+Icons,v3www.apple.com/wss/fonts?families=SF... https://www.apple.com/wss/fonts?families=SF+Pro,v3|SF+Pro+Icons,v3 — 200 — 1.9 KiB — 31 ms — h2https://www.apple.com/wss/fonts?family=SF+Mono&v=2www.apple.com/wss/fonts?family=SF+M... https://www.apple.com/wss/fonts?family=SF+Mono&v=2 — 200 — 1.2 KiB — 29 ms — h2https://www.apple.com/wss/fonts?family=Apple+Icons&v=1www.apple.com/wss/fonts?family=Appl... https://www.apple.com/wss/fonts?family=Apple+Icons&v=1 — 200 — 1.1 KiB — 29 ms — h2https://developer.apple.com/icloud/styles/icloud-common.cssdeveloper.apple.com/icloud/styles/i... https://developer.apple.com/icloud/styles/icloud-common.css — 200 — 3.0 KiB — 11 ms — http/1.1https://developer.apple.com/assets/styles/suggest-lang.css?54232608030developer.apple.com/assets/styles/s... https://developer.apple.com/assets/styles/suggest-lang.css?54232608030 — 200 — 4.1 KiB — 19 ms — http/1.1https://developer.apple.com/assets/scripts/suggest-lang.js?03162626057developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/suggest-lang.js?03162626057 — 200 — 4.6 KiB — 38 ms — http/1.1https://developer.apple.com/assets/styles/globalnav.css?48212635068developer.apple.com/assets/styles/g... https://developer.apple.com/assets/styles/globalnav.css?48212635068 — 200 — 122.4 KiB — 21 ms — http/1.1https://developer.apple.com/assets/scripts/ac-globalnav.built.js?01172638057developer.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/ac-globalnav.built.js?01172638057 — 200 — 15.7 KiB — 41 ms — http/1.1https://developer.apple.com/assets/metrics/scripts/analytics.jsdeveloper.apple.com/assets/metrics/... https://developer.apple.com/assets/metrics/scripts/analytics.js — 200 — 83.1 KiB — 44 ms — http/1.1https://developer.apple.com/assets/styles/localnav.cssdeveloper.apple.com/assets/styles/l... https://developer.apple.com/assets/styles/localnav.css — 200 — 59.7 KiB — 20 ms — http/1.1https://developer.apple.com/assets/scripts/ac-localnav.built.jsdeveloper.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/ac-localnav.built.js — 200 — 51.6 KiB — 44 ms — http/1.1https://developer.apple.com/assets/scripts/localnav.jsdeveloper.apple.com/assets/scripts/... https://developer.apple.com/assets/scripts/localnav.js — 200 — 2.0 KiB — 43 ms — http/1.1https://developer.apple.com/assets/elements/icons/icloud/icloud-96x96_2x.pngdeveloper.apple.com/assets/elements... https://developer.apple.com/assets/elements/icons/icloud/icloud-96x96_2x.png — 200 — 14.7 KiB — 5 ms — http/1.1https://developer.apple.com/icloud/images/screen-hero-large_2x.png?1developer.apple.com/icloud/images/s... https://developer.apple.com/icloud/images/screen-hero-large_2x.png?1 — 200 — 355.1 KiB — 194 ms — http/1.1https://developer.apple.com/assets/elements/icons/xcode-s/xcode-s-96x96_2x.pngdeveloper.apple.com/assets/elements... https://developer.apple.com/assets/elements/icons/xcode-s/xcode-s-96x96_2x.png — 200 — 30.4 KiB — 5 ms — http/1.1https://developer.apple.com/assets/styles/footer.dist.css?54232608030developer.apple.com/assets/styles/f... https://developer.apple.com/assets/styles/footer.dist.css?54232608030 — 200 — 27.9 KiB — 3 ms — http/1.1https://developer.apple.com/assets/styles/language-dropdown.css?54232608030developer.apple.com/assets/styles/l... https://developer.apple.com/assets/styles/language-dropdown.css?54232608030 — 200 — 2.6 KiB — 3 ms — 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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 369ms · 145KB · $5/mo
developer.apple.com
Other
Costly
Execution 218ms
Transfer 94 KB
Monthly Cost $3/mo
Unattributable
Other
Optional
Execution 77ms
Transfer 0 KB
Monthly Cost $1/mo
developer.apple.com
Other
Optional
Execution 74ms
Transfer 52 KB
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • developer.apple.com adds 218ms and costs ~$3/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

developer.apple.com takes 218ms 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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