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Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
81
GRADE
B
FIX
4
REVIEW
4
PASS
7
INFO
2

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

Mobile Desktop
66
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
84
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.
50
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.

3.30 s

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

16.47 s

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

61 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.

4.73 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.

16.55 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
7 PASS 4 REVIEW 4 FIX
F
Page Weight Budget
Action
2.8 MB transferred, 37 requests
FIX
2.8 MB transferred, 37 requests
Warning::
Page weighs 4.3 MB (2.8 MB transferred)
Info::
Fonts are 1.3 MB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 1.3 MB
Warning::
Images are 1.1 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 1.1 MB
Info::
37 HTTP requests
Info::
Estimated 0.58 g CO2 per page load
2.8 MB / 2.4 MB budget
2.8 MB transferred
37 requests
0.58 g CO2 per page load
Fonts 1.3 MiB 49%
Images 1.1 MiB 38%
JavaScript 241.0 KiB 9%
CSS 85.0 KiB 3%
HTML 28.2 KiB 1%
Other 7.5 KiB 0%
Other 471 B 0%
0 2.4 MB 4.9 MB
Over budget

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

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

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 (2.8 MiB of 2.8 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
D
Page Weight Inventory
Action
37 resources · 2.8 MB · 103 KB savings available
FIX
37 resources · 2.8 MB · 103 KB savings available
Warning::
Page weight 1.8 MB over 1MB target
Got: 2.8 MB Expected: ≤ 1 MB
Info::
~103 KB of savings available
Warning::
36 third-party resources (100% of weight)
Info::
2 resources over 200KB
37 resources · 2.8 MiB · 36 third-party 1.8 MiB over 1MB target
Font 49% · 1.3 MiB
Image 38% · 1.1 MiB
JavaScript 9% · 241.0 KiB
CSS 3% · 85.0 KiB
Document 1% · 28.8 KiB
Other 0% · 538 B

~102.6 KiB of savings available

Remove unused JavaScript: 102.6 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.

B
Image Optimization
13 images, 0 KB saveable
REVIEW
13 images, 0 KB saveable
Info::
All images are well-optimized
13 images 1.1 MB
0 oversized -0 KB
5 legacy format
0 missing dimensions CLS risk
B
JS Execution Cost
946ms total JS execution
REVIEW
946ms total JS execution
Warning::
https://github.blog/news-insights/product-news/sun...: 435ms CPU time
Info::
Unattributable: 235ms CPU time
Info::
https://github.blog/wp-content/themes/github-2021/...: 133ms CPU time
Info::
https://js.monitor.azure.com/scripts/c/ms.analytic...: 81ms CPU time
Info::
https://cdnjs.cloudflare.com/ajax/libs/highlight.j...: 62ms CPU time
Warning::
Third-party scripts: 946ms (100% of total)

Main Thread Breakdown

Style & Layout 35% Other 25% Script Evaluation 20% Script Parsing & Compilation 10% Parse HTML & CSS 7%
ScriptTotalScriptingParse/CompileParty
https://github.blog/news-insights/product-news/sunsetting-atom/435ms7ms3ms3rd
Unattributable235ms6ms0ms3rd
https://github.blog/wp-content/themes/github-2021/dist/js/site-script.js?m=1776795618g133ms52ms10ms3rd
https://js.monitor.azure.com/scripts/c/ms.analytics-web-4.js81ms10ms70ms3rd
https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.11.1/highlight.min.js?ver=11.4.062ms52ms9ms3rd
B
JS Bundles
13 scripts, 103 KB unused
REVIEW
13 scripts, 103 KB unused
Warning::
https://js.monitor.azure.com/scripts/c/ms.analytic...: 103 KB unused (88%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://js.monitor.azure.com/scripts/c/ms.analytic...: unminified — 43 KB could be saved
Info::
Total unused JavaScript: 103 KB
103 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://js.monitor.azure.com/scripts/c/ms.analytics-web-4.js118 KB103 KB (88%)✗3rd
https://github.blog/wp-content/themes/github-2021/dist/js/site-script.js?m=1776795618g29 KB—✓3rd
https://github.blog/_static/??-eJx9jdEOwiAMRX9IVlni0Afjt2xAoAzKIiXz860mGp987Tn3FPZN2UrsiWHLPSA1CFFOdUX/Ik2Imskpvs92RQrgsDGkBn+cIbUD/JQ5+uIljBz7osbjqJWNmN23lTFEXurjM0SyuTuZCHs7UZ61oSCJcStXbcxkLqdJn9MTiwNGNQ==4 KB—✓3rd
https://github.blog/wp-includes/js/dist/i18n.min.js?ver=c26c3dc7bed3667933753 KB—✓3rd
https://github.blog/wp-includes/js/dist/url.min.js?m=1774626885g4 KB—✓3rd
https://github.blog/wp-includes/js/dist/api-fetch.min.js?ver=3a4d9af2b423048b0dee3 KB—✓3rd
https://ghcc.githubassets.com/ghcc.min.js18 KB—✓3rd
https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.11.1/highlight.min.js?ver=11.4.037 KB—✓3rd
https://github.blog/wp-content/plugins/page-links-to/dist/new-tab.js?m=1776795618g14 KB—✓3rd
https://analytics.githubassets.com/v1.1.0/hydro-marketing.min.js?ver=6.9.44 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+
Font Loading
3 fonts (1378 KB)
PASS
3 fonts (1378 KB)
Info::
3 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

3

1378 KB total

Render-blocking

0

of 3

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s 14.0 s 16.0 s FCP 3.3 s LCP 16.5 shttps://github.blog/wp-content/themes/github-2021/dist/fonts/mona-sans.woff2mona-sans.woff2 https://github.blog/wp-content/themes/github-2021/dist/fonts/mona-sans.woff2 — 134.4 KiB — 52 ms — font-display: swaphttps://github.blog/wp-content/themes/github-2021/dist/fonts/MonaspaceNeon-Regular.woff2MonaspaceNeon-Regular.w... https://github.blog/wp-content/themes/github-2021/dist/fonts/MonaspaceNeon-Regular.woff2 — 1.2 MiB — 97 ms — font-display: swaphttps://github.blog/wp-content/themes/github-2021/dist/fonts/mona-sans-italic.woff2mona-sans-italic.woff2 https://github.blog/wp-content/themes/github-2021/dist/fonts/mona-sans-italic.woff2 — 41.1 KiB — 8 ms — font-display: swap
mona-sans.woff2 woff2 swap
Size 134 KB
Load time 52 ms
Start 822 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
MonaspaceNeon-Regular.w... woff2 swap
Size 1203 KB
Load time 97 ms
Start 822 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
mona-sans-italic.woff2 woff2 swap
Size 41 KB
Load time 8 ms
Start 1.0 s
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 ~669 KB and ~1338 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
8 hints, 0 missing preconnects
PASS
8 hints, 0 missing preconnects
Info::
Page uses 8 resource hint(s)

Current Resource Hints

preconnect
—
preload
2
dns-prefetch
6
prefetch
—

8 resource hints configured

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
37 requests over 1507ms
INFO
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s 14.0 s 16.0 s FCP 3.3 s LCP 16.5 shttps://atom.io// https://atom.io/ — 301 — 67 B — 296 ms — h2https://github.blog/2022-06-08-sunsetting-atom/github.blog/2022-06-08-sunsetting-a... https://github.blog/2022-06-08-sunsetting-atom/ — 301 — 210 B — 226 ms — h2https://github.blog/engineering/sunsetting-atom/github.blog/engineering/sunsetting-... https://github.blog/engineering/sunsetting-atom/ — 301 — 405 B — 282 ms — h2https://github.blog/news-insights/product-news/sunsetting-atom/github.blog/news-insights/product-n... https://github.blog/news-insights/product-news/sunsetting-atom/ — 200 — 28.2 KiB — 4 ms — h2https://github.blog/_static/??-eJyNjEEOwjAMBD+EMalEAwfEW9rUJJbiNKodAb8ncIEj19mdwXuFsBajYlhzi1wUOxIqDVimSDipkikG7YMw3Lb+BrVnpn1nO/wJWCIhxciW2gzDYXAQEucFF1b7FDLHZPP6+EP9SspGoGHjam/vKhfn/ejPx9GdXt7XRQw=github.blog/_static/??-eJyNjEEOwjAM... https://github.blog/_static/??-eJyNjEEOwjAMBD+EMalEAwfEW9rUJJbiNKodAb8ncIEj19mdwXuFsBajYlhzi1wUOxIqDVimSDipkikG7YMw3Lb+BrVnpn1nO/wJWCIhxciW2gzDYXAQEucFF1b7FDLHZPP6+EP9SspGoGHjam/vKhfn/ejPx9GdXt7XRQw= — 200 — 84.0 KiB — 28 ms — h2https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.11.1/styles/default.min.css?ver=11.4.0cdnjs.cloudflare.com/ajax/libs/high... https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.11.1/styles/default.min.css?ver=11.4.0 — 200 — 1.1 KiB — 83 ms — h3https://github.blog/wp-content/themes/github-2021/dist/fonts/mona-sans.woff2github.blog/wp-content/themes/githu... https://github.blog/wp-content/themes/github-2021/dist/fonts/mona-sans.woff2 — 200 — 134.4 KiB — 52 ms — h2https://github.blog/wp-content/themes/github-2021/dist/fonts/MonaspaceNeon-Regular.woff2github.blog/wp-content/themes/githu... https://github.blog/wp-content/themes/github-2021/dist/fonts/MonaspaceNeon-Regular.woff2 — 200 — 1.2 MiB — 97 ms — h2https://github.blog/wp-content/uploads/2024/06/AI-DarkMode-4.png?w=800github.blog/wp-content/uploads/2024... https://github.blog/wp-content/uploads/2024/06/AI-DarkMode-4.png?w=800 — 200 — 136.6 KiB — 54 ms — h2https://github.blog/wp-content/uploads/2024/05/Enterprise-DarkMode-3.png?w=800github.blog/wp-content/uploads/2024... https://github.blog/wp-content/uploads/2024/05/Enterprise-DarkMode-3.png?w=800 — 200 — 164.6 KiB — 57 ms — h2https://github.blog/wp-content/uploads/2024/07/Screenshot-2024-07-23-at-8.42.45%E2%80%AFAM.png?w=800github.blog/wp-content/uploads/2024... https://github.blog/wp-content/uploads/2024/07/Screenshot-2024-07-23-at-8.42.45%E2%80%AFAM.png?w=800 — 200 — 130.7 KiB — 61 ms — h2https://github.blog/wp-content/uploads/2024/07/Screenshot-2024-07-23-at-8.43.47%E2%80%AFAM.png?w=800github.blog/wp-content/uploads/2024... https://github.blog/wp-content/uploads/2024/07/Screenshot-2024-07-23-at-8.43.47%E2%80%AFAM.png?w=800 — 200 — 223.9 KiB — 67 ms — h2https://github.blog/wp-content/uploads/2024/07/Screenshot-2024-07-23-at-8.44.23%E2%80%AFAM.png?w=800github.blog/wp-content/uploads/2024... https://github.blog/wp-content/uploads/2024/07/Screenshot-2024-07-23-at-8.44.23%E2%80%AFAM.png?w=800 — 200 — 132.9 KiB — 75 ms — h2https://ghcc.githubassets.com/ghcc.min.jsghcc.githubassets.com/ghcc.min.js https://ghcc.githubassets.com/ghcc.min.js — 200 — 17.7 KiB — 87 ms — h2https://js.monitor.azure.com/scripts/c/ms.analytics-web-4.jsjs.monitor.azure.com/scripts/c/ms.a... https://js.monitor.azure.com/scripts/c/ms.analytics-web-4.js — 200 — 117.5 KiB — 177 ms — h2https://github.blog/_static/??-eJx9jdEOwiAMRX9IVlni0Afjt2xAoAzKIiXz860mGp987Tn3FPZN2UrsiWHLPSA1CFFOdUX/Ik2Imskpvs92RQrgsDGkBn+cIbUD/JQ5+uIljBz7osbjqJWNmN23lTFEXurjM0SyuTuZCHs7UZ61oSCJcStXbcxkLqdJn9MTiwNGNQ==github.blog/_static/??-eJx9jdEOwiAM... https://github.blog/_static/??-eJx9jdEOwiAMRX9IVlni0Afjt2xAoAzKIiXz860mGp987Tn3FPZN2UrsiWHLPSA1CFFOdUX/Ik2Imskpvs92RQrgsDGkBn+cIbUD/JQ5+uIljBz7osbjqJWNmN23lTFEXurjM0SyuTuZCHs7UZ61oSCJcStXbcxkLqdJn9MTiwNGNQ== — 200 — 4.4 KiB — 61 ms — h2https://github.blog/wp-includes/js/dist/i18n.min.js?ver=c26c3dc7bed366793375github.blog/wp-includes/js/dist/i18... https://github.blog/wp-includes/js/dist/i18n.min.js?ver=c26c3dc7bed366793375 — 200 — 2.5 KiB — 61 ms — h2https://github.blog/wp-includes/js/dist/url.min.js?m=1774626885ggithub.blog/wp-includes/js/dist/url... https://github.blog/wp-includes/js/dist/url.min.js?m=1774626885g — 200 — 4.1 KiB — 60 ms — h2https://github.blog/wp-includes/js/dist/api-fetch.min.js?ver=3a4d9af2b423048b0deegithub.blog/wp-includes/js/dist/api... https://github.blog/wp-includes/js/dist/api-fetch.min.js?ver=3a4d9af2b423048b0dee — 200 — 2.7 KiB — 60 ms — h2https://github.blog/wp-content/themes/github-2021/dist/js/site-script.js?m=1776795618ggithub.blog/wp-content/themes/githu... https://github.blog/wp-content/themes/github-2021/dist/js/site-script.js?m=1776795618g — 200 — 29.3 KiB — 60 ms — h2https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.11.1/highlight.min.js?ver=11.4.0cdnjs.cloudflare.com/ajax/libs/high... https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.11.1/highlight.min.js?ver=11.4.0 — 200 — 37.5 KiB — 105 ms — h3https://github.blog/wp-content/plugins/page-links-to/dist/new-tab.js?m=1776795618ggithub.blog/wp-content/plugins/page... https://github.blog/wp-content/plugins/page-links-to/dist/new-tab.js?m=1776795618g — 200 — 14.0 KiB — 60 ms — h2https://analytics.githubassets.com/v1.1.0/hydro-marketing.min.js?ver=6.9.4analytics.githubassets.com/v1.1.0/h... https://analytics.githubassets.com/v1.1.0/hydro-marketing.min.js?ver=6.9.4 — 200 — 4.2 KiB — 56 ms — h2https://github.blog/wp-content/uploads/2024/07/Screenshot-2024-07-23-at-8.46.23%E2%80%AFAM.png?w=800github.blog/wp-content/uploads/2024... https://github.blog/wp-content/uploads/2024/07/Screenshot-2024-07-23-at-8.46.23%E2%80%AFAM.png?w=800 — 200 — 146.9 KiB — 75 ms — h2https://github.blog/wp-content/uploads/2024/07/Screenshot-2024-07-23-at-8.47.04%E2%80%AFAM.png?w=800github.blog/wp-content/uploads/2024... https://github.blog/wp-content/uploads/2024/07/Screenshot-2024-07-23-at-8.47.04%E2%80%AFAM.png?w=800 — 200 — 117.6 KiB — 78 ms — h2https://github.blog/wp-content/uploads/2024/07/Icon-Circle.svggithub.blog/wp-content/uploads/2024... https://github.blog/wp-content/uploads/2024/07/Icon-Circle.svg — 200 — 1.1 KiB — 76 ms — h2https://github.blog/wp-content/uploads/2022/05/readme.svggithub.blog/wp-content/uploads/2022... https://github.blog/wp-content/uploads/2022/05/readme.svg — 200 — 810 B — 75 ms — h2https://github.blog/wp-content/uploads/2022/05/actions.svggithub.blog/wp-content/uploads/2022... https://github.blog/wp-content/uploads/2022/05/actions.svg — 200 — 1.1 KiB — 75 ms — h2https://github.blog/wp-content/uploads/2022/05/careers.svggithub.blog/wp-content/uploads/2022... https://github.blog/wp-content/uploads/2022/05/careers.svg — 200 — 1.4 KiB — 75 ms — h2https://stats.wp.com/e-202617.jsstats.wp.com/e-202617.js https://stats.wp.com/e-202617.js — 200 — 1.7 KiB — 38 ms — h2
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s 14.0 s 16.0 s FCP 3.3 s LCP 16.5 shttps://atom.io// https://atom.io/ — 301 — 67 B — 296 ms — h2https://github.blog/2022-06-08-sunsetting-atom/github.blog/2022-06-08-sunsetting-a... https://github.blog/2022-06-08-sunsetting-atom/ — 301 — 210 B — 226 ms — h2https://github.blog/engineering/sunsetting-atom/github.blog/engineering/sunsetting-... https://github.blog/engineering/sunsetting-atom/ — 301 — 405 B — 282 ms — h2https://github.blog/news-insights/product-news/sunsetting-atom/github.blog/news-insights/product-n... https://github.blog/news-insights/product-news/sunsetting-atom/ — 200 — 28.2 KiB — 4 ms — h2https://github.blog/_static/??-eJyNjEEOwjAMBD+EMalEAwfEW9rUJJbiNKodAb8ncIEj19mdwXuFsBajYlhzi1wUOxIqDVimSDipkikG7YMw3Lb+BrVnpn1nO/wJWCIhxciW2gzDYXAQEucFF1b7FDLHZPP6+EP9SspGoGHjam/vKhfn/ejPx9GdXt7XRQw=github.blog/_static/??-eJyNjEEOwjAM... 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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 946ms · 212KB · $3/mo
github.blog
Other
Costly
Execution 435ms
Transfer 28 KB
Monthly Cost $1/mo
Unattributable
Other
Costly
Execution 235ms
Transfer 0 KB
Monthly Cost $1/mo
github.blog
Other
Optional
Execution 133ms
Transfer 29 KB
Monthly Cost $0/mo
js.monitor.azure.com
Other
Optional
Execution 81ms
Transfer 118 KB
Unused 88%
Monthly Cost $0/mo
cdnjs
CDN
Optional
Execution 62ms
Transfer 37 KB
Monthly Cost $0/mo

These scripts may cost more than they're worth

  • github.blog adds 435ms and costs ~$1/month
  • Unattributable adds 235ms and costs ~$1/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

github.blog takes 435ms 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

Unattributable takes 235ms 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

88% of js.monitor.azure.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

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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