Skip to content
https://www.kernel.org

Performance

· 13 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
97
GRADE
A+
FIX
1
REVIEW
2
PASS
9
INFO
1

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

Mobile Desktop
100
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
75
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.
91
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.

241 ms

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

281 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.

0.002

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

241 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.

281 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
13
9 PASS 2 REVIEW 1 FIX
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.
Info::
Last-Modified header present

No Cache-Control header

Adding a Cache-Control header can significantly improve repeat-visit performance.

B
Image Optimization
9 images, 0 KB saveable
REVIEW
9 images, 0 KB saveable
Info::
All images are well-optimized
9 images 35 KB
0 oversized -0 KB
9 legacy format
0 missing dimensions CLS risk
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Page Weight Budget
96 KB transferred, 15 requests
PASS
96 KB transferred, 15 requests
Info::
Page weighs 107 KB (96 KB transferred)
Info::
15 HTTP requests
Info::
Estimated 0.02 g CO2 per page load
96 KB / 2.4 MB budget
96 KB transferred
15 requests
0.02 g CO2 per page load
Fonts 39.7 KiB 42%
Images 34.8 KiB 36%
CSS 13.9 KiB 15%
Other 3.9 KiB 4%
HTML 3.3 KiB 3%
0 2.4 MB 4.9 MB
Under budget
A+
Third-Party Impact
No third-party resources
PASS
No third-party resources
Info::
No third-party resources detected
No third-party resources detected — all resources are first-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+
JS Execution Cost
No JS execution data
PASS
No JS execution data
Info::
No significant JS execution detected

Main Thread Breakdown

Other 45% Style & Layout 38% Script Evaluation 8% Rendering 7%
A+
Font Loading
2 fonts (40 KB)
PASS
2 fonts (40 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

40 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 FCP 241 ms LCP 281 mshttps://www.kernel.org/theme/fonts/oswald-regular-webfont.woff2oswald-regular-webfont.... https://www.kernel.org/theme/fonts/oswald-regular-webfont.woff2 — 20.2 KiB — 0 ms — font-display: swaphttps://www.kernel.org/theme/fonts/oxygen-regular-webfont.woff2oxygen-regular-webfont.... https://www.kernel.org/theme/fonts/oxygen-regular-webfont.woff2 — 19.6 KiB — 0 ms — font-display: swap
oswald-regular-webfont.... woff2 swap
Size 20 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
oxygen-regular-webfont.... woff2 swap
Size 20 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
No JavaScript
PASS
No JavaScript
Info::
No JavaScript bundles
No JavaScript files loaded.
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
15 requests over 0ms
INFO

Performance analysis not available for this result.

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

Send Feedback