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https://kit.svelte.dev

Performance

· 16 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
82
GRADE
B
FIX
2
REVIEW
4
PASS
8
INFO
2

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

Mobile Desktop
89
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
100
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.
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.

2.30 s

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

3.35 s

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

22 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.

2.30 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.

3.36 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
16
8 PASS 4 REVIEW 2 FIX
F
Page Weight Budget
Action
4.0 MB transferred, 73 requests
FIX
4.0 MB transferred, 73 requests
Critical::
Page weighs 5.4 MB (4.0 MB transferred)
Info::
73 HTTP requests
Info::
Estimated 0.83 g CO2 per page load
4.0 MB / 2.4 MB budget
4.0 MB transferred
73 requests
0.83 g CO2 per page load
Other 3.1 MiB 77%
Images 356.2 KiB 9%
Other 351.9 KiB 9%
JavaScript 105.9 KiB 3%
Fonts 69.2 KiB 2%
HTML 23.4 KiB 1%
CSS 22.6 KiB 1%
Other 3.8 KiB 0%
Other 657 B 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Over budget
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 (4.0 MiB of 4.0 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
B
Image Optimization
18 images, 0 KB saveable
REVIEW
18 images, 0 KB saveable
Info::
All images are well-optimized
18 images 356 KB
0 oversized -0 KB
6 legacy format
0 missing dimensions CLS risk
C
JS Execution Cost
Action
1768ms total JS execution
REVIEW
1768ms total JS execution
Warning::
https://svelte.dev/: 706ms CPU time
Warning::
https://svelte.dev/_app/immutable/chunks/DnTnPfQe....: 544ms CPU time
Warning::
Unattributable: 518ms CPU time
Warning::
Third-party scripts: 1768ms (100% of total)

Main Thread Breakdown

Other 45% Script Evaluation 25% Style & Layout 18% Rendering 10%
ScriptTotalScriptingParse/CompileParty
https://svelte.dev/706ms65ms9ms3rd
https://svelte.dev/_app/immutable/chunks/DnTnPfQe.js544ms287ms1ms3rd
Unattributable518ms72ms0ms3rd
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

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+
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 (69 KB)
PASS
3 fonts (69 KB)
Info::
3 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

3

69 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 1.0 s 2.0 s 3.0 s FCP 2.3 s LCP 3.3 shttps://svelte.dev/_app/immutable/assets/eb-garamond-latin-400-normal.DSJrtJSV.woff2eb-garamond-latin-400-n... https://svelte.dev/_app/immutable/assets/eb-garamond-latin-400-normal.DSJrtJSV.woff2 — 21.4 KiB — 0 ms — font-display: swaphttps://svelte.dev/_app/immutable/assets/dm-serif-display-latin-400-normal.C5_t9oOD.woff2dm-serif-display-latin-... https://svelte.dev/_app/immutable/assets/dm-serif-display-latin-400-normal.C5_t9oOD.woff2 — 24.3 KiB — 0 ms — font-display: swaphttps://svelte.dev/_app/immutable/assets/fira-sans-latin-400-normal.a0AnQzuD.woff2fira-sans-latin-400-nor... https://svelte.dev/_app/immutable/assets/fira-sans-latin-400-normal.a0AnQzuD.woff2 — 23.5 KiB — 0 ms — font-display: swap
eb-garamond-latin-400-n... woff2 swap
Size 21 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
dm-serif-display-latin-... woff2 swap
Size 24 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
fira-sans-latin-400-nor... woff2 swap
Size 23 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)
A+
JS Bundles
28 scripts, 0 KB unused
PASS
28 scripts, 0 KB unused
0 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://svelte.dev/_app/immutable/entry/start.Ddn2_gng.js0 KB—✓3rd
https://svelte.dev/_app/immutable/chunks/BbUITsMw.js13 KB—✓3rd
https://svelte.dev/_app/immutable/chunks/2d-wjCb2.js1 KB—✓3rd
https://svelte.dev/_app/immutable/chunks/DnTnPfQe.js23 KB—✓3rd
https://svelte.dev/_app/immutable/chunks/gDVcjQvr.js1 KB—✓3rd
https://svelte.dev/_app/immutable/entry/app.BfHSeXOh.js3 KB—✓3rd
https://svelte.dev/_app/immutable/chunks/Shm_I8ZE.js1 KB—✓3rd
https://svelte.dev/_app/immutable/chunks/Dr15X4ZF.js0 KB—✓3rd
https://svelte.dev/_app/immutable/chunks/cnniI1X3.js0 KB—✓3rd
https://svelte.dev/_app/immutable/nodes/0.CPp9tl-V.js6 KB—✓3rd
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
3 hints, 0 missing preconnects
PASS
3 hints, 0 missing preconnects
Info::
Page uses 3 resource hint(s)

Current Resource Hints

preconnect
—
preload
3
dns-prefetch
—
prefetch
—

3 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
73 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
100% of JavaScript execution is third-party
First-party Third-party 1768ms · 47KB · $23/mo
svelte.dev
Other
Costly
Execution 706ms
Transfer 23 KB
Monthly Cost $9/mo
svelte.dev
Other
Costly
Execution 544ms
Transfer 23 KB
Monthly Cost $7/mo
Unattributable
Other
Costly
Execution 518ms
Transfer 0 KB
Monthly Cost $7/mo

These scripts may cost more than they're worth

  • svelte.dev adds 706ms and costs ~$9/month
  • svelte.dev adds 544ms and costs ~$7/month
  • Unattributable adds 518ms and costs ~$7/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

svelte.dev takes 706ms 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

svelte.dev takes 544ms 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 518ms 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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