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Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
91
GRADE
A
FIX
2
REVIEW
1
PASS
9
INFO
2

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

Mobile Desktop
99
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.
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.

791 ms

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

811 ms

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.

0.030

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

791 ms

Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.

813 ms

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
14
9 PASS 1 REVIEW 2 FIX
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 (457.8 KiB of 458.0 KiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
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.

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

Green Hosting

No green hosting detected

A+
Page Weight Budget
458 KB transferred, 26 requests
PASS
458 KB transferred, 26 requests
Info::
Page weighs 829 KB (458 KB transferred)
Info::
26 HTTP requests
Info::
Estimated 0.09 g CO2 per page load
458 KB / 2.4 MB budget
458 KB transferred
26 requests
0.09 g CO2 per page load
Other 159.3 KiB 35%
Fonts 141.9 KiB 31%
JavaScript 79.0 KiB 17%
CSS 54.3 KiB 12%
HTML 12.0 KiB 3%
Other 8.0 KiB 2%
Images 2.9 KiB 1%
Other 639 B 0%
0 2.4 MB 4.9 MB
Under budget
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
Image Optimization
5 images, 0 KB saveable
PASS
5 images, 0 KB saveable
Info::
All images are well-optimized
5 images 3 KB
0 oversized -0 KB
3 legacy format
0 missing dimensions CLS risk
A+
JS Execution Cost
283ms total JS execution
PASS
283ms total JS execution
Info::
Unattributable: 102ms CPU time
Info::
https://nixos.org/_astro/Asciinema.astro_astro_typ...: 100ms CPU time
Info::
https://nixos.org/: 81ms CPU time
Warning::
Third-party scripts: 283ms (100% of total)

Main Thread Breakdown

Other 35% Script Evaluation 31% Style & Layout 25% Rendering 6%
ScriptTotalScriptingParse/CompileParty
Unattributable102ms27ms0ms3rd
https://nixos.org/_astro/Asciinema.astro_astro_type_script_index_0_lang.9jNJCMF_.js100ms53ms0ms3rd
https://nixos.org/81ms1ms0ms3rd
A+
Font Loading
4 fonts (142 KB)
PASS
4 fonts (142 KB)
Info::
4 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

4

142 KB total

Render-blocking

0

of 4

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s FCP 791 ms LCP 811 mshttps://nixos.org/_astro/roboto-flex-latin-wdth-normal.BPCCEOJP.woff2roboto-flex-latin-wdth-... https://nixos.org/_astro/roboto-flex-latin-wdth-normal.BPCCEOJP.woff2 — 58.3 KiB — 0 ms — font-display: swaphttps://nixos.org/fonts/route159/Route159-Heavy.woffRoute159-Heavy.woff https://nixos.org/fonts/route159/Route159-Heavy.woff — 23.8 KiB — 0 ms — font-display: swaphttps://nixos.org/fonts/route159/Route159-Bold.woffRoute159-Bold.woff https://nixos.org/fonts/route159/Route159-Bold.woff — 24.3 KiB — 0 ms — font-display: swaphttps://nixos.org/_astro/fira-code-latin-wght-normal.CHoedHDv.woff2fira-code-latin-wght-no... https://nixos.org/_astro/fira-code-latin-wght-normal.CHoedHDv.woff2 — 35.5 KiB — 0 ms — font-display: swap
roboto-flex-latin-wdth-... woff2 swap
Size 58 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Route159-Heavy.woff woff swap
Size 24 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
Route159-Bold.woff woff swap
Size 24 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
fira-code-latin-wght-no... woff2 swap
Size 36 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 ~14 KB and ~28 ms

A+
JS Bundles
2 scripts, 0 KB unused
PASS
2 scripts, 0 KB unused
0 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://nixos.org/_astro/Asciinema.astro_astro_type_script_index_0_lang.9jNJCMF_.js61 KB—✓3rd
https://nixos.org/_astro/Layout.astro_astro_type_script_index_0_lang.Cg311B8L.js18 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
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
Network Waterfall
26 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 283ms · 73KB · €3/mo
Unattributable
Other
Optional
Execution 102ms
Transfer 0 KB
Monthly Cost €1/mo
nixos.org
Other
Optional
Execution 100ms
Transfer 61 KB
Monthly Cost €1/mo
nixos.org
Other
Optional
Execution 81ms
Transfer 12 KB
Monthly Cost €1/mo

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

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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