Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.

SCORE

GRADE

FIX

REVIEW

PASS

INFO

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

Mobile Desktop

Performance

Accessibility

100

Best Practices

SEO

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

3.90 s

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

4.89 s

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.

0.000

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

3.90 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.

4.90 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

11 PASS 2 REVIEW 2 FIX

Third-Party Impact

Action

98% third-party, 0 ms blocking

FIX

98% third-party, 0 ms blocking

Third-party code accounts for 98% of page weight (560.6 KiB of 571.2 KiB)

Third-party blocking time is low (0 ms)

98%

First-party Third-party

HTTP Caching

Action

no-store (uncacheable)

FIX

no-store (uncacheable)

Cache-Control: no-store prevents all caching

Intentional for dynamic content, but increases server load for every page view.

Got: no-cache, no-store, must-revalidate

No ETag or Last-Modified header

Conditional requests (304 Not Modified) are not possible without validators.

Cache-Control

no-cache, no-store, must-revalidate

Directive	Value	Meaning
no-cache	—	Cache but always revalidate first
no-store	—	Never cache this response
must-revalidate	—	Must recheck with server after expiry

Image Optimization

34 images, 0 KB saveable

REVIEW

34 images, 0 KB saveable

All images are well-optimized

34 images 303 KB

0 oversized -0 KB

13 legacy format

0 missing dimensions CLS risk

JS Execution Cost

Action

1031ms total JS execution

REVIEW

1031ms total JS execution

Unattributable: 512ms CPU time

https://lichess.org/: 455ms CPU time

https://lichess1.org/assets/compiled/site.TUQXHEA3...: 65ms CPU time

Third-party scripts: 576ms (56% of total)

Main Thread Breakdown

Other 35% Script Evaluation 31% Style & Layout 22% Rendering 6% Parse HTML & CSS 4%

Script	Total	Scripting	Parse/Compile	Party
Unattributable	512ms	126ms	0ms	3rd
https://lichess.org/	455ms	38ms	2ms	1st
https://lichess1.org/assets/compiled/site.TUQXHEA3.js	65ms	26ms	0ms	3rd

A+

Page Weight Budget

571 KB transferred, 83 requests

PASS

571 KB transferred, 83 requests

Page weighs 934 KB (571 KB transferred)

83 HTTP requests

Estimated 0.12 g CO2 per page load

571 KB transferred

83 requests

0.12 g CO2 per page load

Images 302.8 KiB 53%

JavaScript 132.1 KiB 23%

Fonts 95.9 KiB 17%

CSS 23.5 KiB 4%

HTML 10.0 KiB 2%

Other 6.3 KiB 1%

Other 632 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

All text resources are properly compressed.

A+

Font Loading

4 fonts (96 KB)

PASS

4 fonts (96 KB)

4 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

96 KB total

Render-blocking

of 4

Dominant font-display

swap

Most common across fonts

Font loading timeline

Transfer FOIT (block) FOUT (swap)

lichess.2a2cb52f.woff2 woff2 swap

Size 15 KB

Load time 98 ms

Start 109 ms

Risk FOUT — text flashes from fallback to web font

noto-sans-latin.086bfca... woff2 swap

Size 35 KB

Load time 180 ms

Start 109 ms

Risk FOUT — text flashes from fallback to web font

roboto-latin.20b535fa.w... woff2 swap

Size 39 KB

Load time 203 ms

Start 110 ms

Risk FOUT — text flashes from fallback to web font

lichess-chess.02d5eb8f.... woff2 swap

Size 6 KB

Load time 173 ms

Start 110 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

38 scripts, 0 KB unused

PASS

38 scripts, 0 KB unused

0 KB unused JavaScript

Downloaded but never executed on this page.

Script	Size	Unused	Minified	Party
https://lichess1.org/assets/compiled/manifest.1fe45971.js	17 KB	—	✓	3rd
https://lichess1.org/assets/compiled/i18n/site.en-US.4d4d13554b4a.js	15 KB	—	✓	3rd
https://lichess1.org/assets/compiled/i18n/timeago.en-US.c5b087b5c613.js	1 KB	—	✓	3rd
https://lichess1.org/assets/compiled/i18n/preferences.en-US.904ece6f121e.js	2 KB	—	✓	3rd
https://lichess1.org/assets/compiled/i18n/variant.en-US.aff7e7ce3fe8.js	1 KB	—	✓	3rd
https://lichess1.org/assets/compiled/site.TUQXHEA3.js	12 KB	—	✓	3rd
https://lichess1.org/assets/compiled/lib.REPI3M76.js	2 KB	—	✓	3rd
https://lichess1.org/assets/compiled/lib.AYW6K5CT.js	1 KB	—	✓	3rd
https://lichess1.org/assets/compiled/lib.QM5RCGHR.js	1 KB	—	✓	3rd
https://lichess1.org/assets/compiled/lib.DEGIMVFB.js	1 KB	—	✓	3rd

A+

Resource Caching

All resources properly cached

PASS

All resources properly cached

No caching issues found

All static resources have appropriate caching headers.

A+

Critical Rendering Path

No render-blocking resources

PASS

No render-blocking resources

No render-blocking resources detected

A+

Resource Hints

17 hints, 0 missing preconnects

PASS

17 hints, 0 missing preconnects

Page uses 17 resource hint(s)

Current Resource Hints

preconnect

—

preload

dns-prefetch

—

prefetch

—

17 resource hints configured

Page Weight Inventory

83 resources · 571 KB · 0 KB savings available

PASS

83 resources · 571 KB · 0 KB savings available

Within 1MB page-weight target

Got: 571 KB

81 third-party resources (98% of weight)

83 resources · 571.2 KiB · 81 third-party Within 1MB page-weight target

Image 54% · 309.1 KiB

JavaScript 23% · 132.1 KiB

Font 17% · 95.9 KiB

CSS 4% · 23.5 KiB

Document 2% · 10.0 KiB

Other 0% · 632 B

#	Resource	Type	Size	Cache	Unused	3rd party	Issues

83 resources			571.2 KiB

A+

Render-Blocking Resources

No render-blocking resources detected

PASS

No render-blocking resources detected

No render-blocking resources detected in <head>

A+

Third-Party Resources

No third-party resources detected

PASS

No third-party resources detected

A+

Green Hosting

Whether the site is served from green-energy infrastructure

PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: OVHcloud

Network Waterfall

83 requests over 488ms

INFO

HTML JavaScript CSS Images Fonts XHR/Fetch Other

Third-Party Script Cost

Per-script blocking time, transfer cost, and cache headers

INFO

56% of JavaScript execution is third-party

First-party Third-party 576ms · 12KB · £6/mo

Script	Category	Execution	Transfer	Unused	Monthly Cost	Verdict
Unattributable Unattributable	Other	512ms	0 KB	—	£5/mo	Costly
lichess1.org lichess1.org	Other	65ms	12 KB	—	£1/mo	Optional

Unattributable

Other

Costly

Execution 512ms

Transfer 0 KB

Monthly Cost £5/mo

lichess1.org

Other

Optional

Execution 65ms

Transfer 12 KB

Monthly Cost £1/mo

These scripts may cost more than they're worth

Unattributable adds 512ms and costs ~£5/month

56% of JavaScript execution time comes from third-party scripts.

Why this matters

Third-party scripts (analytics, ads, social, A/B testing) often dominate execution time — every one is a perf-and-privacy tax.

Learn more ▾

Each third-party script is a black box: you don't control when it loads, what it executes, or how much it grows. They often account for a major share of total blocking time on average sites (HTTP Archive's Web Almanac documents the trend). Audit which ones you actually need, defer the rest, and use facade patterns (lite-youtube, lite-vimeo) for embedded media.

Source: web.dev / HTTP Archive Web Almanac

Unattributable takes 512ms 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.