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https://ustc.edu.cn

Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
86
GRADE
B
FIX
1
REVIEW
4
PASS
10
INFO
2

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

Mobile Desktop
86
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
52
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.
73
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.

1.80 s

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

3.45 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.

5.33 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.

3.45 s

Page Load Progression

907 ms
1.8 s
2.7 s
3.6 s
4.5 s
5.4 s
6.4 s
7.3 s
Checks
17
10 PASS 4 REVIEW 1 FIX
F
Page Weight Budget
Action
2.9 MB transferred, 57 requests
FIX
2.9 MB transferred, 57 requests
Warning::
Page weighs 3.2 MB (2.9 MB transferred)
Warning::
Images are 2.7 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 2.7 MB
Info::
57 HTTP requests
Info::
Estimated 0.60 g CO2 per page load
2.9 MB / 2.4 MB budget
2.9 MB transferred
57 requests
0.60 g CO2 per page load
Images 2.7 MiB 95%
JavaScript 116.5 KiB 4%
CSS 18.0 KiB 1%
HTML 7.1 KiB 0%
Fonts 3.0 KiB 0%
Other 1.1 KiB 0%
0 2.4 MB 4.9 MB
Over budget

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

C
Image Optimization
Action
25 images, 0 KB saveable
REVIEW
25 images, 0 KB saveable
Warning::
https://ustc.edu.cn/news/images/4054C9236D1DF77880... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://ustc.edu.cn/news/images/jiuyezhidao.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://ustc.edu.cn/news/images/l3.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://ustc.edu.cn/news/images/blue.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://ustc.edu.cn/news/images/l1.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://ustc.edu.cn/news/images/l2.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
25 images 2.7 MB
0 oversized -0 KB
25 legacy format
6 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

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

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 Execution Cost
895ms total JS execution
REVIEW
895ms total JS execution
Warning::
Unattributable: 369ms CPU time
Warning::
https://ustc.edu.cn/: 296ms CPU time
Info::
https://ustc.edu.cn/news/js/jquery.js: 231ms CPU time
Info::
Third-party scripts: 369ms (41% of total)

Main Thread Breakdown

Other 47% Script Evaluation 21% Style & Layout 16% Script Parsing & Compilation 6% Rendering 6% Parse HTML & CSS 4%
ScriptTotalScriptingParse/CompileParty
Unattributable369ms7ms0ms3rd
https://ustc.edu.cn/296ms13ms4ms1st
https://ustc.edu.cn/news/js/jquery.js231ms144ms34ms1st
C
Page Weight Inventory
Action
57 resources · 2.9 MB · 35 KB savings available
REVIEW
57 resources · 2.9 MB · 35 KB savings available
Warning::
Page weight 1.9 MB over 1MB target
Got: 2.9 MB Expected: ≤ 1 MB
Info::
4 resources over 200KB
57 resources · 2.9 MiB · 0 third-party 1.9 MiB over 1MB target
Image 95% · 2.7 MiB
JavaScript 4% · 116.5 KiB
CSS 1% · 18.0 KiB
Document 0% · 7.1 KiB
Font 0% · 3.0 KiB

~35.4 KiB of savings available

Remove unused JavaScript: 35.4 KiB
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Third-Party Impact
No third-party resources
PASS
No third-party resources
Info::
No third-party resources detected
No third-party resources detected — all resources are first-party.
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
1 fonts (3 KB)
PASS
1 fonts (3 KB)
Info::
1 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

1

3 KB total

Render-blocking

0

of 1

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 1.8 s LCP 3.5 shttps://ustc.edu.cn/news/fonts/fontello.wofffontello.woff https://ustc.edu.cn/news/fonts/fontello.woff — 3.0 KiB — 870 ms — font-display: swap
fontello.woff woff swap
Size 3 KB
Load time 870 ms
Start 2.5 s
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
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 ~1 KB and ~2 ms

A
JS Bundles
17 scripts, 35 KB unused
PASS
17 scripts, 35 KB unused
Warning::
https://ustc.edu.cn/news/js/jquery.js: 35 KB unused (42%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://ustc.edu.cn/news/js/jquery.js: unminified — 41 KB could be saved
Info::
Total unused JavaScript: 35 KB
35 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://ustc.edu.cn/news/js/jquery.js84 KB35 KB (42%)✗1st
https://ustc.edu.cn/news/js/jquery.sudy.wp.visitcount.js2 KB—✓1st
https://ustc.edu.cn/news/js/jquery.sudynav.js2 KB—✓1st
https://ustc.edu.cn/news/js/modernizr.js4 KB—✓1st
https://ustc.edu.cn/_sitegray/_sitegray.js0 KB—✓1st
https://ustc.edu.cn/system/resource/js/vsbscreen.min.js1 KB—✓1st
https://ustc.edu.cn/system/resource/js/counter.js1 KB—✓1st
https://ustc.edu.cn/news/js/public.js1 KB—✓1st
https://ustc.edu.cn/news/js/jquery-migrate.min.js4 KB—✓1st
https://ustc.edu.cn/system/resource/js/dynclicks.js1 KB—✓1st

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

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
A+
HTTP Caching
max-age=600 (10 minutes)
PASS
max-age=600 (10 minutes)
Info::
Cache-Control header is set
Got: private, max-age=600
Info::
Effective TTL: 10 minutes (max-age=600)
Info::
ETag present — enables conditional (304) responses
Info::
Last-Modified header present
Cache-Control

private, max-age=600

DirectiveValueMeaning
private—Only browser cache, not CDN/proxy
max-age600Cache for 10 minutes
Effective TTL: 600 seconds
Network Waterfall
57 requests over 7551ms
INFO
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s 7.0 s FCP 1.8 s LCP 3.5 shttps://ustc.edu.cn// https://ustc.edu.cn/ — 200 — 7.1 KiB — 905 ms — h2https://ustc.edu.cn/news/css/simplenews.css/news/css/simplenews.css https://ustc.edu.cn/news/css/simplenews.css — 200 — 3.8 KiB — 1.2 s — h2https://ustc.edu.cn/news/css/sudynav.css/news/css/sudynav.css https://ustc.edu.cn/news/css/sudynav.css — 200 — 844 B — 611 ms — h2https://ustc.edu.cn/news/js/jquery.js/news/js/jquery.js https://ustc.edu.cn/news/js/jquery.js — 200 — 84.2 KiB — 1.5 s — h2https://ustc.edu.cn/news/js/jquery.sudy.wp.visitcount.js/news/js/jquery.sudy.wp.visitcount.... https://ustc.edu.cn/news/js/jquery.sudy.wp.visitcount.js — 200 — 1.6 KiB — 317 ms — h2https://ustc.edu.cn/news/js/jquery.sudynav.js/news/js/jquery.sudynav.js https://ustc.edu.cn/news/js/jquery.sudynav.js — 200 — 1.5 KiB — 320 ms — h2https://ustc.edu.cn/news/js/modernizr.js/news/js/modernizr.js https://ustc.edu.cn/news/js/modernizr.js — 200 — 3.7 KiB — 1.5 s — h2https://ustc.edu.cn/news/css/slick.css/news/css/slick.css https://ustc.edu.cn/news/css/slick.css — 200 — 1.1 KiB — 611 ms — h2https://ustc.edu.cn/news/css/index.css/news/css/index.css https://ustc.edu.cn/news/css/index.css — 200 — 5.0 KiB — 612 ms — h2https://ustc.edu.cn/news/css/theme0.css/news/css/theme0.css https://ustc.edu.cn/news/css/theme0.css — 200 — 931 B — 318 ms — h2https://ustc.edu.cn/news/css/theme1.css/news/css/theme1.css https://ustc.edu.cn/news/css/theme1.css — 200 — 876 B — 608 ms — h2https://ustc.edu.cn/news/css/theme2.css/news/css/theme2.css https://ustc.edu.cn/news/css/theme2.css — 200 — 910 B — 1.2 s — h2https://ustc.edu.cn/news/css/theme3.css/news/css/theme3.css https://ustc.edu.cn/news/css/theme3.css — 200 — 916 B — 623 ms — h2https://ustc.edu.cn/news/css/media.css/news/css/media.css https://ustc.edu.cn/news/css/media.css — 200 — 2.1 KiB — 1.2 s — h2https://ustc.edu.cn/news/css/index.vsb.css/news/css/index.vsb.css https://ustc.edu.cn/news/css/index.vsb.css — 200 — 614 B — 1.2 s — h2https://ustc.edu.cn/_sitegray/_sitegray_d.css/_sitegray/_sitegray_d.css https://ustc.edu.cn/_sitegray/_sitegray_d.css — 200 — 289 B — 316 ms — h2https://ustc.edu.cn/_sitegray/_sitegray.js/_sitegray/_sitegray.js https://ustc.edu.cn/_sitegray/_sitegray.js — 200 — 413 B — 1.5 s — h2https://ustc.edu.cn/index.vsb.css/index.vsb.css https://ustc.edu.cn/index.vsb.css — 200 — 652 B — 310 ms — h2https://ustc.edu.cn/system/resource/js/vsbscreen.min.js/system/resource/js/vsbscreen.min.j... https://ustc.edu.cn/system/resource/js/vsbscreen.min.js — 200 — 1.5 KiB — 1.5 s — h2https://ustc.edu.cn/system/resource/js/counter.js/system/resource/js/counter.js https://ustc.edu.cn/system/resource/js/counter.js — 200 — 1.0 KiB — 1.5 s — h2https://ustc.edu.cn/news/js/public.js/news/js/public.js https://ustc.edu.cn/news/js/public.js — 200 — 1.1 KiB — 1.5 s — h2https://ustc.edu.cn/news/js/jquery-migrate.min.js/news/js/jquery-migrate.min.js https://ustc.edu.cn/news/js/jquery-migrate.min.js — 200 — 4.3 KiB — 1.5 s — h2https://ustc.edu.cn/system/resource/js/dynclicks.js/system/resource/js/dynclicks.js https://ustc.edu.cn/system/resource/js/dynclicks.js — 200 — 1.3 KiB — 1.5 s — h2https://ustc.edu.cn/system/resource/js/openlink.js/system/resource/js/openlink.js https://ustc.edu.cn/system/resource/js/openlink.js — 200 — 600 B — 1.5 s — h2https://ustc.edu.cn/system/resource/js/base64.js/system/resource/js/base64.js https://ustc.edu.cn/system/resource/js/base64.js — 200 — 1.6 KiB — 1.5 s — h2https://ustc.edu.cn/system/resource/js/formfunc.js/system/resource/js/formfunc.js https://ustc.edu.cn/system/resource/js/formfunc.js — 200 — 939 B — 1.5 s — h2https://ustc.edu.cn/images/ss.png/images/ss.png https://ustc.edu.cn/images/ss.png — 200 — 736 B — 302 ms — h2https://ustc.edu.cn/images/19/08/05/1bv2xhbf6r/img01.jpg/images/19/08/05/1bv2xhbf6r/img01.j... https://ustc.edu.cn/images/19/08/05/1bv2xhbf6r/img01.jpg — 200 — 8.5 KiB — 303 ms — h2https://ustc.edu.cn/images/19/08/05/1bv2xhbf6r/img02.jpg/images/19/08/05/1bv2xhbf6r/img02.j... https://ustc.edu.cn/images/19/08/05/1bv2xhbf6r/img02.jpg — 200 — 9.0 KiB — 306 ms — h2https://ustc.edu.cn/images/19/08/05/1bv2xhbf6r/img03.jpg/images/19/08/05/1bv2xhbf6r/img03.j... https://ustc.edu.cn/images/19/08/05/1bv2xhbf6r/img03.jpg — 200 — 10.0 KiB — 308 ms — h2
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s 7.0 s FCP 1.8 s LCP 3.5 shttps://ustc.edu.cn// https://ustc.edu.cn/ — 200 — 7.1 KiB — 905 ms — h2https://ustc.edu.cn/news/css/simplenews.css/news/css/simplenews.css https://ustc.edu.cn/news/css/simplenews.css — 200 — 3.8 KiB — 1.2 s — h2https://ustc.edu.cn/news/css/sudynav.css/news/css/sudynav.css https://ustc.edu.cn/news/css/sudynav.css — 200 — 844 B — 611 ms — h2https://ustc.edu.cn/news/js/jquery.js/news/js/jquery.js https://ustc.edu.cn/news/js/jquery.js — 200 — 84.2 KiB — 1.5 s — h2https://ustc.edu.cn/news/js/jquery.sudy.wp.visitcount.js/news/js/jquery.sudy.wp.visitcount.... https://ustc.edu.cn/news/js/jquery.sudy.wp.visitcount.js — 200 — 1.6 KiB — 317 ms — h2https://ustc.edu.cn/news/js/jquery.sudynav.js/news/js/jquery.sudynav.js https://ustc.edu.cn/news/js/jquery.sudynav.js — 200 — 1.5 KiB — 320 ms — h2https://ustc.edu.cn/news/js/modernizr.js/news/js/modernizr.js https://ustc.edu.cn/news/js/modernizr.js — 200 — 3.7 KiB — 1.5 s — h2https://ustc.edu.cn/news/css/slick.css/news/css/slick.css https://ustc.edu.cn/news/css/slick.css — 200 — 1.1 KiB — 611 ms — h2https://ustc.edu.cn/news/css/index.css/news/css/index.css https://ustc.edu.cn/news/css/index.css — 200 — 5.0 KiB — 612 ms — h2https://ustc.edu.cn/news/css/theme0.css/news/css/theme0.css https://ustc.edu.cn/news/css/theme0.css — 200 — 931 B — 318 ms — h2https://ustc.edu.cn/news/css/theme1.css/news/css/theme1.css https://ustc.edu.cn/news/css/theme1.css — 200 — 876 B — 608 ms — h2https://ustc.edu.cn/news/css/theme2.css/news/css/theme2.css https://ustc.edu.cn/news/css/theme2.css — 200 — 910 B — 1.2 s — h2https://ustc.edu.cn/news/css/theme3.css/news/css/theme3.css https://ustc.edu.cn/news/css/theme3.css — 200 — 916 B — 623 ms — h2https://ustc.edu.cn/news/css/media.css/news/css/media.css https://ustc.edu.cn/news/css/media.css — 200 — 2.1 KiB — 1.2 s — h2https://ustc.edu.cn/news/css/index.vsb.css/news/css/index.vsb.css https://ustc.edu.cn/news/css/index.vsb.css — 200 — 614 B — 1.2 s — h2https://ustc.edu.cn/_sitegray/_sitegray_d.css/_sitegray/_sitegray_d.css https://ustc.edu.cn/_sitegray/_sitegray_d.css — 200 — 289 B — 316 ms — h2https://ustc.edu.cn/_sitegray/_sitegray.js/_sitegray/_sitegray.js https://ustc.edu.cn/_sitegray/_sitegray.js — 200 — 413 B — 1.5 s — h2https://ustc.edu.cn/index.vsb.css/index.vsb.css https://ustc.edu.cn/index.vsb.css — 200 — 652 B — 310 ms — h2https://ustc.edu.cn/system/resource/js/vsbscreen.min.js/system/resource/js/vsbscreen.min.j... https://ustc.edu.cn/system/resource/js/vsbscreen.min.js — 200 — 1.5 KiB — 1.5 s — h2https://ustc.edu.cn/system/resource/js/counter.js/system/resource/js/counter.js https://ustc.edu.cn/system/resource/js/counter.js — 200 — 1.0 KiB — 1.5 s — h2https://ustc.edu.cn/news/js/public.js/news/js/public.js https://ustc.edu.cn/news/js/public.js — 200 — 1.1 KiB — 1.5 s — h2https://ustc.edu.cn/news/js/jquery-migrate.min.js/news/js/jquery-migrate.min.js https://ustc.edu.cn/news/js/jquery-migrate.min.js — 200 — 4.3 KiB — 1.5 s — h2https://ustc.edu.cn/system/resource/js/dynclicks.js/system/resource/js/dynclicks.js https://ustc.edu.cn/system/resource/js/dynclicks.js — 200 — 1.3 KiB — 1.5 s — h2https://ustc.edu.cn/system/resource/js/openlink.js/system/resource/js/openlink.js https://ustc.edu.cn/system/resource/js/openlink.js — 200 — 600 B — 1.5 s — h2https://ustc.edu.cn/system/resource/js/base64.js/system/resource/js/base64.js https://ustc.edu.cn/system/resource/js/base64.js — 200 — 1.6 KiB — 1.5 s — h2https://ustc.edu.cn/system/resource/js/formfunc.js/system/resource/js/formfunc.js https://ustc.edu.cn/system/resource/js/formfunc.js — 200 — 939 B — 1.5 s — h2https://ustc.edu.cn/images/ss.png/images/ss.png https://ustc.edu.cn/images/ss.png — 200 — 736 B — 302 ms — h2https://ustc.edu.cn/images/19/08/05/1bv2xhbf6r/img01.jpg/images/19/08/05/1bv2xhbf6r/img01.j... https://ustc.edu.cn/images/19/08/05/1bv2xhbf6r/img01.jpg — 200 — 8.5 KiB — 303 ms — 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h2https://ustc.edu.cn/news/css/globe.jpg/news/css/globe.jpg https://ustc.edu.cn/news/css/globe.jpg — 200 — 158.3 KiB — 1.5 s — h2https://ustc.edu.cn/news/images/nav_btn_open.jpg/news/images/nav_btn_open.jpg https://ustc.edu.cn/news/images/nav_btn_open.jpg — 200 — 3.1 KiB — 574 ms — h2https://ustc.edu.cn/news/css/wif.jpg/news/css/wif.jpg https://ustc.edu.cn/news/css/wif.jpg — 200 — 8.4 KiB — 577 ms — h2https://ustc.edu.cn/news/css/more-1-hover.png/news/css/more-1-hover.png https://ustc.edu.cn/news/css/more-1-hover.png — 200 — 1.4 KiB — 577 ms — h2https://ustc.edu.cn/news/fonts/fontello.woff/news/fonts/fontello.woff https://ustc.edu.cn/news/fonts/fontello.woff — 200 — 3.0 KiB — 870 ms — h2https://ustc.edu.cn/__local/D/57/DA/94AAEAEF3830793410880F98321_D453E135_1E27F.jpg/__local/D/57/DA/94AAEAEF3830793410... https://ustc.edu.cn/__local/D/57/DA/94AAEAEF3830793410880F98321_D453E135_1E27F.jpg — 200 — 121.2 KiB — 946 ms — h2https://ustc.edu.cn/news/css/sh_1.jpg/news/css/sh_1.jpg 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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
41% of JavaScript execution is third-party
First-party Third-party 369ms · 0KB · ¥18/mo
Unattributable
Other
Costly
Execution 369ms
Transfer 0 KB
Monthly Cost ¥18/mo

These scripts may cost more than they're worth

  • Unattributable adds 369ms and costs ~¥18/month

41% of JavaScript execution time comes from third-party scripts.

Why this matters

Third-party scripts (analytics, ads, social, A/B testing) often dominate execution time — every one is a perf-and-privacy tax.

Learn more ▾

Each third-party script is a black box: you don't control when it loads, what it executes, or how much it grows. They often account for a major share of total blocking time on average sites (HTTP Archive's Web Almanac documents the trend). Audit which ones you actually need, defer the rest, and use facade patterns (lite-youtube, lite-vimeo) for embedded media.

Source: web.dev / HTTP Archive Web Almanac

Unattributable takes 369ms 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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