Skip to content
https://lwn.net

Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
97
GRADE
A+
FIX
0
REVIEW
2
PASS
13
INFO
2

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.
100
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.

918 ms

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

918 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.

1.03 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.

918 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
17
13 PASS 2 REVIEW
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, no-cache
REVIEW
max-age=0, no-cache
Info::
Cache-Control header is set
Got: max-age=0, no-cache
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

max-age=0, no-cache

DirectiveValueMeaning
max-age0Cache for 0 seconds
no-cache—Cache but always revalidate first
A+
Page Weight Budget
25 KB transferred, 5 requests
PASS
25 KB transferred, 5 requests
Info::
Page weighs 58 KB (25 KB transferred)
Info::
5 HTTP requests
Info::
Estimated 0.01 g CO2 per page load
25 KB / 2.4 MB budget
25 KB transferred
5 requests
0.01 g CO2 per page load
HTML 11.1 KiB 45%
Images 5.7 KiB 23%
CSS 5.6 KiB 23%
Other 2.3 KiB 9%
0 2.4 MB 4.9 MB
Under budget
A
Third-Party Impact
32% third-party, 0 ms blocking
PASS
32% third-party, 0 ms blocking
Info::
Third-party code accounts for 32% of page weight (8.0 KiB of 24.7 KiB)
Info::
Third-party blocking time is low (0 ms)
68%
32%
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
Image Optimization
2 images, 0 KB saveable
PASS
2 images, 0 KB saveable
Warning::
https://static.lwn.net/images/lcorner-ss.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
2 images 6 KB
0 oversized -0 KB
1 legacy format
1 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

A+
JS Execution Cost
232ms total JS execution
PASS
232ms total JS execution
Info::
https://lwn.net/: 156ms CPU time
Info::
Unattributable: 76ms CPU time
Info::
Third-party scripts: 76ms (33% of total)

Main Thread Breakdown

Style & Layout 46% Other 39% Rendering 8% Script Evaluation 4% Parse HTML & CSS 3%
ScriptTotalScriptingParse/CompileParty
https://lwn.net/156ms3ms1ms1st
Unattributable76ms5ms0ms3rd
A+
Font Loading
No web fonts (system fonts)
PASS
No web fonts (system fonts)
Info::
No web fonts loaded — system fonts are fastest
No web fonts loaded — system fonts are optimal.
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
A+
Page Weight Inventory
5 resources · 25 KB · 0 KB savings available
PASS
5 resources · 25 KB · 0 KB savings available
Info::
Within 1MB page-weight target
Got: 25 KB
Info::
3 third-party resources (32% of weight)
5 resources · 24.7 KiB · 3 third-party Within 1MB page-weight target
Document 45% · 11.1 KiB
Image 32% · 8.0 KiB
CSS 23% · 5.6 KiB
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
5 requests over 862ms
INFO
0 ms 200 ms 400 ms 600 ms 800 ms FCP 918 ms LCP 918 mshttps://lwn.net// https://lwn.net/ — 200 — 11.1 KiB — 377 ms — http/1.1https://lwn.net/CSS/lwn/CSS/lwn https://lwn.net/CSS/lwn — 200 — 5.6 KiB — 103 ms — http/1.1https://static.lwn.net/images/logo/barepenguin-70.webpstatic.lwn.net/images/logo/barepeng... https://static.lwn.net/images/logo/barepenguin-70.webp — 200 — 2.3 KiB — 453 ms — http/1.1https://static.lwn.net/images/lcorner-ss.pngstatic.lwn.net/images/lcorner-ss.pn... https://static.lwn.net/images/lcorner-ss.png — 200 — 3.4 KiB — 457 ms — http/1.1https://static.lwn.net/images/favicon.pngstatic.lwn.net/images/favicon.png https://static.lwn.net/images/favicon.png — 200 — 2.3 KiB — 96 ms — http/1.1
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
33% of JavaScript execution is third-party
First-party Third-party 76ms · 0KB · €1/mo
Unattributable
Other
Optional
Execution 76ms
Transfer 0 KB
Monthly Cost €1/mo

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.

Send Feedback