Performance

· 15 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

100

SEO

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

1.26 s

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

2.36 s

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

56 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.006

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

1.55 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.

2.42 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

6 PASS 4 REVIEW 3 FIX

Page Weight Budget

Action

9.3 MB transferred, 224 requests

FIX

9.3 MB transferred, 224 requests

Page weighs 11.6 MB (9.3 MB transferred)

Images are 7.7 MB — compress or use modern formats

Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.

Got: 7.7 MB

JavaScript is 776 KB — consider code splitting or lazy loading

Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.

Got: 776 KB

Fonts are 563 KB — consider subsetting or using system fonts

Subset fonts to include only used characters, or switch to system font stacks.

Got: 563 KB

224 HTTP requests — consider bundling or reducing

Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.

Estimated 1.9 g CO2 per page load

9.3 MB transferred

224 requests

1.9 g CO2 per page load

Images 7.7 MiB 83%

JavaScript 776.5 KiB 8%

Fonts 563.0 KiB 6%

Other 129.4 KiB 1%

CSS 66.4 KiB 1%

Other 35.0 KiB 0%

HTML 16.7 KiB 0%

Other 7.8 KiB 0%

Other 6.1 KiB 0%

Other 1.6 KiB 0%

0 2.4 MB 4.9 MB

Over budget

Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.

Why this matters

Image bandwidth is high — modern formats (WebP/AVIF) and resizing typically cut it 50%+.

Source: web.dev

Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.

Why this matters

JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.

Source: web.dev

Subset fonts to include only used characters, or switch to system font stacks.

Why this matters

Font payload is large — subset to used glyphs only, or fall back to system fonts (zero load time).

Source: web.dev font loading

Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.

Why this matters

High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.

Source: web.dev

Third-Party Impact

Action

83% third-party, 0 ms blocking

FIX

83% third-party, 0 ms blocking

Third-party code accounts for 83% of page weight (7.7 MiB of 9.3 MiB)

Third-party blocking time is low (0 ms)

17%

83%

First-party Third-party

Page Weight Inventory

Action

224 resources · 9.3 MB · 50 KB savings available

FIX

224 resources · 9.3 MB · 50 KB savings available

Page weight 8.3 MB over 1MB target

Got: 9.3 MB Expected: ≤ 1 MB

~50 KB of savings available

41 third-party resources (83% of weight)

7 resources over 200KB

224 resources · 9.3 MiB · 41 third-party 8.3 MiB over 1MB target

Image 83% · 7.7 MiB

JavaScript 8% · 776.5 KiB

Font 6% · 563.0 KiB

Other 2% · 166.1 KiB

CSS 1% · 66.4 KiB

Document 0% · 16.7 KiB

Media 0% · 6.1 KiB

~50.2 KiB of savings available

Remove unused JavaScript: 50.2 KiB

#	Resource	Type	Size	Cache	Unused	3rd party	Issues

224 resources			9.3 MiB

Image Optimization

40 images, 0 KB saveable

REVIEW

40 images, 0 KB saveable

All images are well-optimized

40 images 7.7 MB

0 oversized -0 KB

40 legacy format

0 missing dimensions CLS risk

JS Execution Cost

Action

1059ms total JS execution

REVIEW

1059ms total JS execution

https://mastodon.social/packs/assets/polyfills-CTA...: 567ms CPU time

Unattributable: 293ms CPU time

https://mastodon.social/: 73ms CPU time

https://mastodon.social/packs/react-dom-Dj0fTDzk.j...: 70ms CPU time

https://mastodon.social/packs/react-spring_web.mod...: 57ms CPU time

Third-party scripts: 293ms (28% of total)

Main Thread Breakdown

Script Evaluation 52% Other 30% Style & Layout 10% Parse HTML & CSS 4%

Script	Total	Scripting	Parse/Compile	Party
https://mastodon.social/packs/assets/polyfills-CTAUVuFB.js	567ms	453ms	0ms	1st
Unattributable	293ms	83ms	0ms	3rd
https://mastodon.social/	73ms	1ms	0ms	1st
https://mastodon.social/packs/react-dom-Dj0fTDzk.js	70ms	44ms	0ms	1st
https://mastodon.social/packs/react-spring_web.modern-JXeU3pDC.js	57ms	20ms	0ms	1st

JS Bundles

159 scripts, 50 KB unused

REVIEW

159 scripts, 50 KB unused

https://mastodon.social/packs/compose_form_contain...: 50 KB unused (42%)

Consider code splitting or tree shaking to reduce unused code.

Total unused JavaScript: 50 KB

50 KB unused JavaScript

Downloaded but never executed on this page.

Script	Size	Unused	Minified	Party
https://mastodon.social/packs/compose_form_container-CM_jQYh3.js	119 KB	50 KB (42%)	✓	1st
https://mastodon.social/packs/assets/polyfills-CTAUVuFB.js	19 KB	—	✓	1st
https://mastodon.social/packs/assets/common-Jsh12Tqs.js	1 KB	—	✓	1st
https://mastodon.social/packs/dist-ByY3fW40.js	2 KB	—	✓	1st
https://mastodon.social/packs/intl/en-BzUYU0Yc.js	23 KB	—	✓	1st
https://mastodon.social/packs/assets/application-C3rvZT82.js	20 KB	—	✓	1st
https://mastodon.social/packs/fast-memoize-Dz9wbbMP.js	1 KB	—	✓	1st
https://mastodon.social/packs/chunk-DENWwQMA.js	1 KB	—	✓	1st
https://mastodon.social/packs/preload-helper-cEh0PfmN.js	1 KB	—	✓	1st
https://mastodon.social/packs/store-D0tdxE3j.js	37 KB	—	✓	1st

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Green Hosting

Action

Whether the site is served from green-energy infrastructure

REVIEW

Green Hosting

No green hosting detected

A+

Text Compression

All text resources are compressed

PASS

All text resources are compressed

All text resources are properly compressed.

A+

Font Loading

3 fonts (563 KB)

PASS

3 fonts (563 KB)

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

Web fonts

563 KB total

Render-blocking

of 3

Dominant font-display

swap

Most common across fonts

Font loading timeline

Transfer FOIT (block) FOUT (swap)

roboto-regular-webfont-... woff2 swap

Size 187 KB

Load time 10 ms

Start 214 ms

Risk FOUT — text flashes from fallback to web font

Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need

roboto-medium-webfont-B... woff2 swap

Size 187 KB

Load time 19 ms

Start 624 ms

Risk FOUT — text flashes from fallback to web font

Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need

roboto-bold-webfont-DbQ... woff2 swap

Size 189 KB

Load time 22 ms

Start 625 ms

Risk FOUT — text flashes from fallback to web font

Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need

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 ~281 KB and ~562 ms

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

No optimization needed

PASS

No optimization needed

No resource hint issues

A+

HTTP Caching

max-age=15 (15 seconds)

PASS

max-age=15 (15 seconds)

Cache-Control header is set

Got: max-age=15, public, stale-while-revalidate=30, stale-if-error=86400

Effective TTL: 15 seconds (max-age=15)

ETag present — enables conditional (304) responses

Cache-Control

max-age=15, public, stale-while-revalidate=30, stale-if-error=86400

Directive	Value	Meaning
max-age	15	Cache for 15 seconds
public	—	Any cache may store this response
stale-while-revalidate	30	Serve stale for 30 seconds while fetching fresh
stale-if-error	86400

Effective TTL: 15 seconds

Network Waterfall

224 requests over 1420ms

INFO

HTML JavaScript CSS Images Fonts XHR/Fetch Other

Third-Party Script Cost

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

INFO

28% of JavaScript execution is third-party

First-party Third-party 293ms · 0KB · €2/mo

Script	Category	Execution	Transfer	Unused	Monthly Cost	Verdict
Unattributable Unattributable	Other	293ms	0 KB	—	€2/mo	Costly

Unattributable

Other

Costly

Execution 293ms

Transfer 0 KB

Monthly Cost €2/mo

These scripts may cost more than they're worth

Unattributable adds 293ms and costs ~€2/month

Unattributable takes 293ms 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.

Browse & Analyze

Learn

Performance

Page Load Progression

Green Hosting

Font loading timeline

Optimization checklist

These scripts may cost more than they're worth