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https://zed.dev

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
83
GRADE
B
FIX
2
REVIEW
3
PASS
7
INFO
2

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

Mobile Desktop
52
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
80
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.
92
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.

594 ms

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

1.80 s

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

32.94 s

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.

8.62 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.

38.21 s

Page Load Progression

1.9 s
3.9 s
5.8 s
7.8 s
9.7 s
11.6 s
13.6 s
15.5 s
Checks
14
7 PASS 3 REVIEW 2 FIX
F
Page Weight Budget
Action
3.0 MB transferred, 196 requests
FIX
3.0 MB transferred, 196 requests
Warning::
Page weighs 7.5 MB (3.0 MB transferred)
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
Warning::
JavaScript is 793 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 793 KB
Info::
Fonts are 762 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 762 KB
Warning::
196 HTTP requests — consider bundling or reducing
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
Info::
Estimated 0.62 g CO2 per page load
3.0 MB / 2.4 MB budget
3.0 MB transferred
196 requests
0.62 g CO2 per page load
Images 1.2 MiB 39%
JavaScript 793.2 KiB 26%
Fonts 762.5 KiB 25%
HTML 168.3 KiB 6%
Other 81.2 KiB 3%
CSS 41.7 KiB 1%
Other 1.5 KiB 0%
Other 0 B 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

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

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

F
JS Execution Cost
Action
44771ms total JS execution
FIX
44771ms total JS execution
Warning::
https://zed.dev/_next/static/chunks/9175677c-1b928...: 28499ms CPU time
Warning::
https://zed.dev/_next/static/chunks/3589-5a52e6382...: 10546ms CPU time
Warning::
https://zed.dev/_next/static/chunks/9619-b9f5b8713...: 2477ms CPU time
Warning::
https://zed.dev/_next/static/chunks/1929-38b078550...: 1064ms CPU time
Warning::
https://zed.dev/_next/static/chunks/7725-58431a478...: 996ms CPU time
Info::
Third-party scripts: 347ms (1% of total)

Main Thread Breakdown

Other 94% Script Evaluation 4%
ScriptTotalScriptingParse/CompileParty
https://zed.dev/_next/static/chunks/9175677c-1b928a0b61c19e42.js28499ms89ms3ms1st
https://zed.dev/_next/static/chunks/3589-5a52e63828192df1.js10546ms266ms1ms1st
https://zed.dev/_next/static/chunks/9619-b9f5b871350ea0ae.js2477ms9ms2ms1st
https://zed.dev/_next/static/chunks/1929-38b078550affd7fb.js1064ms857ms3ms1st
https://zed.dev/_next/static/chunks/7725-58431a4787f9111a.js996ms18ms2ms1st
https://zed.dev/590ms16ms57ms1st
Unattributable294ms16ms0ms3rd
https://zed.dev/_next/static/chunks/171-7a9d999412ca0248.js180ms161ms1ms1st
https://zed.dev/_next/static/chunks/6251-8d52ff516a090115.js71ms42ms1ms1st
https://www.googletagmanager.com/gtag/js?id=AW-1796067630954ms43ms10ms3rd
B
Image Optimization
111 images, 0 KB saveable
REVIEW
111 images, 0 KB saveable
Info::
All images are well-optimized
111 images 1.2 MB
0 oversized -0 KB
7 legacy format
0 missing dimensions CLS risk
B
JS Bundles
54 scripts, 132 KB unused
REVIEW
54 scripts, 132 KB unused
Warning::
https://www.googletagmanager.com/gtag/js?id=AW-179...: 64 KB unused (44%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://zed.dev/_next/static/chunks/5523-96f14a5cd...: 39 KB unused (78%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://zed.dev/_next/static/chunks/8503-549245938...: 29 KB unused (75%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 132 KB
132 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtag/js?id=AW-17960676309145 KB64 KB (44%)✓3rd
https://zed.dev/_next/static/chunks/5523-96f14a5cd8d4697b.js50 KB39 KB (78%)✓1st
https://zed.dev/_next/static/chunks/8503-549245938b7c8790.js39 KB29 KB (75%)✓1st
https://zed.dev/_next/static/chunks/webpack-2b126fc0edee5b1d.js2 KB—✓1st
https://zed.dev/_next/static/chunks/9175677c-1b928a0b61c19e42.js54 KB—✓1st
https://zed.dev/_next/static/chunks/1929-38b078550affd7fb.js32 KB—✓1st
https://zed.dev/_next/static/chunks/main-app-4fd10662623aa408.js0 KB—✓1st
https://zed.dev/_next/static/chunks/9529-660cf35110185575.js9 KB—✓1st
https://zed.dev/_next/static/chunks/8761-9e32eb59cb2e368d.js16 KB—✓1st
https://zed.dev/_next/static/chunks/9345-f94afcd26be89760.js5 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

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

B
HTTP Caching
public, max-age=0, must-revalidate
REVIEW
public, max-age=0, must-revalidate
Info::
Cache-Control header is set
Got: public, max-age=0, must-revalidate
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

public, max-age=0, must-revalidate

DirectiveValueMeaning
public—Any cache may store this response
max-age0Cache for 0 seconds
must-revalidate—Must recheck with server after expiry
A+
Third-Party Impact
9% third-party, 0 ms blocking
PASS
9% third-party, 0 ms blocking
Info::
Third-party code accounts for 9% of page weight (280.3 KiB of 3.0 MiB)
Info::
Third-party blocking time is low (0 ms)
91%
First-party Third-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
14 fonts (762 KB)
PASS
14 fonts (762 KB)
Info::
14 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

14

762 KB total

Render-blocking

0

of 14

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 FCP 594 ms LCP 1.8 shttps://zed.dev/_next/static/media/0ad30d1b4531f9e9-s.p.woff20ad30d1b4531f9e9-s.p.woff2 https://zed.dev/_next/static/media/0ad30d1b4531f9e9-s.p.woff2 — 26.9 KiB — 0 ms — font-display: swaphttps://zed.dev/_next/static/media/0d5927bcd2da94b8-s.p.woff20d5927bcd2da94b8-s.p.woff2 https://zed.dev/_next/static/media/0d5927bcd2da94b8-s.p.woff2 — 138.1 KiB — 0 ms — font-display: swaphttps://zed.dev/_next/static/media/1041824d5f477f6b-s.p.woff21041824d5f477f6b-s.p.woff2 https://zed.dev/_next/static/media/1041824d5f477f6b-s.p.woff2 — 40.4 KiB — 0 ms — font-display: swaphttps://zed.dev/_next/static/media/179d7f9da167b110-s.p.woff2179d7f9da167b110-s.p.woff2 https://zed.dev/_next/static/media/179d7f9da167b110-s.p.woff2 — 43.6 KiB — 0 ms — font-display: swaphttps://zed.dev/_next/static/media/3a30c733247faf0b-s.p.woff23a30c733247faf0b-s.p.woff2 https://zed.dev/_next/static/media/3a30c733247faf0b-s.p.woff2 — 29.7 KiB — 0 ms — font-display: swaphttps://zed.dev/_next/static/media/40e24582d8f682d9-s.p.woff240e24582d8f682d9-s.p.woff2 https://zed.dev/_next/static/media/40e24582d8f682d9-s.p.woff2 — 160.4 KiB — 0 ms — font-display: swaphttps://zed.dev/_next/static/media/64b7d03ab5ef000d-s.p.woff264b7d03ab5ef000d-s.p.woff2 https://zed.dev/_next/static/media/64b7d03ab5ef000d-s.p.woff2 — 27.5 KiB — 0 ms — font-display: swaphttps://zed.dev/_next/static/media/64bcbd4d7db4ef3a-s.p.woff264bcbd4d7db4ef3a-s.p.woff2 https://zed.dev/_next/static/media/64bcbd4d7db4ef3a-s.p.woff2 — 61.9 KiB — 0 ms — font-display: swaphttps://zed.dev/_next/static/media/a08768ff0b9f433b-s.p.woff2a08768ff0b9f433b-s.p.woff2 https://zed.dev/_next/static/media/a08768ff0b9f433b-s.p.woff2 — 40.9 KiB — 0 ms — font-display: swaphttps://zed.dev/_next/static/media/a59897eca4c0e06d-s.p.woff2a59897eca4c0e06d-s.p.woff2 https://zed.dev/_next/static/media/a59897eca4c0e06d-s.p.woff2 — 28.4 KiB — 0 ms — font-display: swaphttps://zed.dev/_next/static/media/af04a9c2068a2eb2-s.p.woff2af04a9c2068a2eb2-s.p.woff2 https://zed.dev/_next/static/media/af04a9c2068a2eb2-s.p.woff2 — 44.5 KiB — 0 ms — font-display: swaphttps://zed.dev/_next/static/media/b1846daa82471f57-s.p.woff2b1846daa82471f57-s.p.woff2 https://zed.dev/_next/static/media/b1846daa82471f57-s.p.woff2 — 28.2 KiB — 0 ms — font-display: swaphttps://zed.dev/_next/static/media/eea37e7ecdfe969d-s.p.woff2eea37e7ecdfe969d-s.p.woff2 https://zed.dev/_next/static/media/eea37e7ecdfe969d-s.p.woff2 — 28.6 KiB — 0 ms — font-display: swaphttps://zed.dev/_next/static/media/f00a8cab8c12a6ea-s.p.woff2f00a8cab8c12a6ea-s.p.woff2 https://zed.dev/_next/static/media/f00a8cab8c12a6ea-s.p.woff2 — 63.4 KiB — 0 ms — font-display: swap
0ad30d1b4531f9e9-s.p.woff2 woff2 swap
Size 27 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
0d5927bcd2da94b8-s.p.woff2 woff2 swap
Size 138 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
1041824d5f477f6b-s.p.woff2 woff2 swap
Size 40 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
179d7f9da167b110-s.p.woff2 woff2 swap
Size 44 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
3a30c733247faf0b-s.p.woff2 woff2 swap
Size 30 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
40e24582d8f682d9-s.p.woff2 woff2 swap
Size 160 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
64b7d03ab5ef000d-s.p.woff2 woff2 swap
Size 27 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
64bcbd4d7db4ef3a-s.p.woff2 woff2 swap
Size 62 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
a08768ff0b9f433b-s.p.woff2 woff2 swap
Size 41 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
a59897eca4c0e06d-s.p.woff2 woff2 swap
Size 28 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
af04a9c2068a2eb2-s.p.woff2 woff2 swap
Size 44 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
b1846daa82471f57-s.p.woff2 woff2 swap
Size 28 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
eea37e7ecdfe969d-s.p.woff2 woff2 swap
Size 29 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
f00a8cab8c12a6ea-s.p.woff2 woff2 swap
Size 63 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 ~149 KB and ~298 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
A+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Cloudflare

Network Waterfall
196 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
1% of JavaScript execution is third-party
First-party Third-party 347ms · 145KB · $5/mo
Unattributable
Other
Costly
Execution 294ms
Transfer 0 KB
Monthly Cost $4/mo
Google Tag Manager
Tag Manager
Optional
Execution 54ms
Transfer 145 KB
Unused 44%
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • Unattributable adds 294ms and costs ~$4/month

Unattributable takes 294ms 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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