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Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
71
GRADE
C
FIX
4
REVIEW
3
PASS
5
INFO
2

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

Mobile Desktop
80
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.
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.

923 ms

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

1.91 s

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

201 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.

2.11 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.

4.53 s

Page Load Progression

588 ms
1.2 s
1.8 s
2.4 s
2.9 s
3.5 s
4.1 s
4.7 s
Checks
14
5 PASS 3 REVIEW 4 FIX
F
Page Weight Budget
Action
4.4 MB transferred, 151 requests
FIX
4.4 MB transferred, 151 requests
Critical::
Page weighs 12.5 MB (4.4 MB transferred)
Warning::
JavaScript is 1.7 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.7 MB
Warning::
Images are 1.2 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 1.2 MB
Info::
CSS is 273 KB — consider purging unused styles
Remove unused CSS rules with tools like PurgeCSS to reduce stylesheet size.
Got: 273 KB
Info::
Fonts are 251 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 251 KB
Warning::
151 HTTP requests — consider bundling or reducing
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
Info::
Estimated 0.92 g CO2 per page load
4.4 MB / 2.4 MB budget
4.4 MB transferred
151 requests
0.92 g CO2 per page load
JavaScript 1.7 MiB 39%
Images 1.2 MiB 28%
Other 806.8 KiB 18%
CSS 273.0 KiB 6%
Fonts 251.5 KiB 6%
HTML 128.1 KiB 3%
Other 16.8 KiB 0%
Other 4.4 KiB 0%
Other 2.3 KiB 0%
Other 192 B 0%
0 2.4 MB 4.9 MB
Over budget

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

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

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

Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.

Why this matters

High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.

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 (4.2 MiB of 4.4 MiB)
Info::
Third-party blocking time is low (0 ms)
97%
First-party Third-party
F
JS Execution Cost
Action
4253ms total JS execution
FIX
4253ms total JS execution
Warning::
https://github.githubassets.com/assets/chunk-39118...: 2564ms CPU time
Warning::
https://github.githubassets.com/assets/react-lib-a...: 513ms CPU time
Warning::
https://github.com/: 391ms CPU time
Warning::
https://github.githubassets.com/assets/64247-7de91...: 308ms CPU time
Info::
Unattributable: 170ms CPU time
Warning::
Third-party scripts: 3861ms (91% of total)

Main Thread Breakdown

Other 66% Script Evaluation 19% Style & Layout 9% Script Parsing & Compilation 3%
ScriptTotalScriptingParse/CompileParty
https://github.githubassets.com/assets/chunk-39118-a79af489cc7bc7cc.js2564ms83ms1ms3rd
https://github.githubassets.com/assets/react-lib-a4cf89fce9a1300a.js513ms374ms17ms3rd
https://github.com/391ms2ms0ms1st
https://github.githubassets.com/assets/64247-7de91c52a8aca0eb.js308ms65ms1ms3rd
Unattributable170ms17ms0ms3rd
https://github.githubassets.com/assets/landing-pages-c18ba2fdd1c5392f.js120ms98ms22ms3rd
https://github.githubassets.com/assets/behaviors-ea20a2c6238da250.js109ms41ms5ms3rd
https://github.githubassets.com/assets/46752-46c707717fcbe6a9.js77ms40ms1ms3rd
F
JS Bundles
Action
96 scripts, 664 KB unused
FIX
96 scripts, 664 KB unused
Warning::
https://github.githubassets.com/assets/landing-pag...: 304 KB unused (86%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://github.githubassets.com/assets/primer-reac...: 64 KB unused (53%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://github.githubassets.com/assets/react-lib-a...: 51 KB unused (59%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://github.githubassets.com/assets/48761-4941f...: 48 KB unused (42%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://github.githubassets.com/assets/behaviors-e...: 47 KB unused (82%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 664 KB
664 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://github.githubassets.com/assets/landing-pages-c18ba2fdd1c5392f.js353 KB304 KB (86%)✓3rd
https://github.githubassets.com/assets/primer-react-72d2ec7521017972.js121 KB64 KB (53%)✓3rd
https://github.githubassets.com/assets/react-lib-a4cf89fce9a1300a.js87 KB51 KB (59%)✓3rd
https://github.githubassets.com/assets/48761-4941fce410205fe2.js114 KB48 KB (42%)✓3rd
https://github.githubassets.com/assets/behaviors-ea20a2c6238da250.js57 KB47 KB (82%)✓3rd
https://github.githubassets.com/assets/37826-b3ebde81e7762221.js58 KB43 KB (74%)✓3rd
https://github.githubassets.com/assets/6572-01263ee51465ffb1.js98 KB38 KB (39%)✓3rd
https://github.githubassets.com/assets/react-core-9efb35432aeb5ac0.js57 KB38 KB (66%)✓3rd
https://github.githubassets.com/assets/70641-5a6ec3de78151c22.js98 KB30 KB (31%)✓3rd
https://github.githubassets.com/assets/85897-345989e6728659d7.js15 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

C
Image Optimization
Action
18 images, 0 KB saveable
REVIEW
18 images, 0 KB saveable
Warning::
https://images.ctfassets.net/8aevphvgewt8/g1XhuDG7... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://images.ctfassets.net/8aevphvgewt8/6Qr8Snm4... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
18 images 1.2 MB
0 oversized -0 KB
14 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

C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

B
HTTP Caching
max-age=0, private, must-revalidate
REVIEW
max-age=0, private, must-revalidate
Info::
Cache-Control header is set
Got: max-age=0, private, must-revalidate
Info::
ETag present — enables conditional (304) responses
Cache-Control

max-age=0, private, must-revalidate

DirectiveValueMeaning
max-age0Cache for 0 seconds
private—Only browser cache, not CDN/proxy
must-revalidate—Must recheck with server after expiry
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
2 fonts (251 KB)
PASS
2 fonts (251 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

251 KB total

Render-blocking

0

of 2

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s 1.5 s 2.0 s FCP 923 ms LCP 1.9 shttps://github.githubassets.com/assets/MonaSansVF-wdth-wght-opsz-902d64c7ad02.woff2MonaSansVF-wdth-wght-op... https://github.githubassets.com/assets/MonaSansVF-wdth-wght-opsz-902d64c7ad02.woff2 — 214.6 KiB — 0 ms — font-display: swaphttps://github.githubassets.com/assets/MonaSansMonoVF-wght-04a1e3036ddf.woff2MonaSansMonoVF-wght-04a... https://github.githubassets.com/assets/MonaSansMonoVF-wght-04a1e3036ddf.woff2 — 36.9 KiB — 0 ms — font-display: swap
MonaSansVF-wdth-wght-op... woff2 swap
Size 215 KB
Load time 0 ms
Start 0 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
MonaSansMonoVF-wght-04a... woff2 swap
Size 37 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)

Fixing the unchecked items could save ~107 KB and ~214 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
151 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
91% of JavaScript execution is third-party
First-party Third-party 3861ms · 540KB · $51/mo
github.githubassets.com
Other
Costly
Execution 2564ms
Transfer 10 KB
Monthly Cost $34/mo
github.githubassets.com
Other
Costly
Execution 513ms
Transfer 87 KB
Unused 59%
Monthly Cost $7/mo
github.githubassets.com
Other
Costly
Execution 308ms
Transfer 8 KB
Monthly Cost $4/mo
Unattributable
Other
Optional
Execution 170ms
Transfer 0 KB
Monthly Cost $2/mo
github.githubassets.com
Other
Optional
Execution 120ms
Transfer 353 KB
Unused 86%
Monthly Cost $2/mo
github.githubassets.com
Other
Optional
Execution 109ms
Transfer 57 KB
Unused 82%
Monthly Cost $1/mo
github.githubassets.com
Other
Optional
Execution 77ms
Transfer 26 KB
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • github.githubassets.com adds 2564ms and costs ~$34/month
  • github.githubassets.com adds 513ms and costs ~$7/month
  • github.githubassets.com adds 308ms and costs ~$4/month

91% 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.githubassets.com takes 2564ms 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

github.githubassets.com takes 513ms 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

59% of github.githubassets.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

github.githubassets.com takes 308ms 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

86% of github.githubassets.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

82% of github.githubassets.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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