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

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.

1.00 s

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

1.02 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.

0.008

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

1.00 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.

1.02 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

8 PASS 3 REVIEW 2 FIX

Third-Party Impact

Action

72% third-party, 0 ms blocking

FIX

72% third-party, 0 ms blocking

Third-party code accounts for 72% of page weight (500.5 KiB of 692.7 KiB)

Third-party blocking time is low (0 ms)

28%

72%

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

No ETag or Last-Modified header

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

Cache-Control

private, no-cache, no-store, must-revalidate

Directive	Value	Meaning
private	—	Only browser cache, not CDN/proxy
no-cache	—	Cache but always revalidate first
no-store	—	Never cache this response
must-revalidate	—	Must recheck with server after expiry

Image Optimization

4 images, 0 KB saveable

REVIEW

4 images, 0 KB saveable

https://static.whatsapp.net/rsrc.php/yY/r/_mMwO8HK... is missing width/height — may cause layout shift

Set explicit width and height to prevent CLS.

https://static.whatsapp.net/rsrc.php/yJ/r/twC7frrX... is missing width/height — may cause layout shift

Set explicit width and height to prevent CLS.

4 images 8 KB

0 oversized -0 KB

4 legacy format

2 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

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

JS Bundles

13 scripts, 83 KB unused

REVIEW

13 scripts, 83 KB unused

https://static.whatsapp.net/rsrc.php/v4/y6/r/n80KC...: 52 KB unused (51%)

Consider code splitting or tree shaking to reduce unused code.

https://static.whatsapp.net/rsrc.php/v4i7M54/ya/l/...: 31 KB unused (79%)

Consider code splitting or tree shaking to reduce unused code.

Total unused JavaScript: 83 KB

83 KB unused JavaScript

Downloaded but never executed on this page.

Script	Size	Unused	Minified	Party
https://static.whatsapp.net/rsrc.php/v4/y6/r/n80KC3B7ON5.js	101 KB	52 KB (51%)	✓	3rd
https://static.whatsapp.net/rsrc.php/v4i7M54/ya/l/en_US-j/m8jtobM0BaT.js	39 KB	31 KB (79%)	✓	3rd
https://static.whatsapp.net/rsrc.php/v4/yQ/r/bag6ibmFYGc.js	5 KB	—	✓	3rd
https://static.whatsapp.net/rsrc.php/v4/yl/r/5TReKLCGPcC.js	0 KB	—	✓	3rd
https://static.whatsapp.net/rsrc.php/v4/yR/r/MzhkMBApLms.js	18 KB	—	✓	3rd
https://static.whatsapp.net/rsrc.php/v4/yz/r/6_kfQYonLR-.js	15 KB	—	✓	3rd
https://static.whatsapp.net/rsrc.php/v4/yd/r/0TQ-JFWuwSs.js	1 KB	—	✓	3rd
https://static.whatsapp.net/rsrc.php/v4/yQ/r/6G9Xg5DVlKP.js	1 KB	—	✓	3rd
https://static.whatsapp.net/rsrc.php/v4ibQ14/yT/l/en_US-j/WsphHKb4vs6.js	13 KB	—	✓	3rd
https://chat.whatsapp.com/ajax/bz?__a=1&__ccg=UNKNOWN&__dyn=7xe6E5aQ1PyUbFp41twpUnwgU29zE6u7E3rw5ux609vCwjE1EE2Cw8G0um4o5-0me0sy0ny0RE2Jw8W1uw2oE17U2ZwrU1Xo1UU1JE&__hs=20564.BP%3Awhatsapp_www_pkg.2.0...0&__hsi=7631289646584058378&__req=1&__rev=1037799039&__s=2nwd74%3Abru6ow%3Axvkkl0&__user=0&dpr=2&jazoest=21902&lsd=NoYkSvTGubrM034Dn58vYn	0 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

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+

Page Weight Budget

693 KB transferred, 25 requests

PASS

693 KB transferred, 25 requests

Page weighs 1.6 MB (693 KB transferred)

Fonts are 273 KB — consider subsetting or using system fonts

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

Got: 273 KB

25 HTTP requests

Estimated 0.14 g CO2 per page load

693 KB transferred

25 requests

0.14 g CO2 per page load

Fonts 272.9 KiB 39%

JavaScript 194.1 KiB 28%

Other 111.0 KiB 16%

HTML 41.7 KiB 6%

Other 39.6 KiB 6%

CSS 25.4 KiB 4%

Images 8.0 KiB 1%

0 2.4 MB 4.9 MB

Under budget

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

A+

Text Compression

All text resources are compressed

PASS

All text resources are compressed

All text resources are properly compressed.

A+

JS Execution Cost

356ms total JS execution

PASS

356ms total JS execution

https://chat.whatsapp.com/: 164ms CPU time

Unattributable: 121ms CPU time

https://static.whatsapp.net/rsrc.php/v4/y6/r/n80KC...: 71ms CPU time

Third-party scripts: 192ms (54% of total)

Main Thread Breakdown

Other 32% Script Evaluation 32% Style & Layout 20% Script Parsing & Compilation 7% Parse HTML & CSS 4%

Script	Total	Scripting	Parse/Compile	Party
https://chat.whatsapp.com/	164ms	35ms	5ms	1st
Unattributable	121ms	2ms	0ms	3rd
https://static.whatsapp.net/rsrc.php/v4/y6/r/n80KC3B7ON5.js	71ms	53ms	12ms	3rd

A+

Font Loading

1 fonts (273 KB)

PASS

1 fonts (273 KB)

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

Web fonts

273 KB total

Render-blocking

of 1

Dominant font-display

swap

Most common across fonts

Font loading timeline

Transfer FOIT (block) FOUT (swap)

fQtw5exLIdT.woff2 woff2 swap

Size 273 KB

Load time 27 ms

Start 605 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 ~136 KB and ~272 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

Page Weight Inventory

25 resources · 693 KB · 83 KB savings available

PASS

25 resources · 693 KB · 83 KB savings available

Within 1MB page-weight target

Got: 693 KB

~83 KB of savings available

20 third-party resources (72% of weight)

1 resources over 200KB

25 resources · 692.7 KiB · 20 third-party Within 1MB page-weight target

JavaScript 44% · 305.1 KiB

Font 39% · 272.9 KiB

Document 12% · 81.2 KiB

CSS 4% · 25.4 KiB

Image 1% · 8.0 KiB

~82.6 KiB of savings available

Remove unused JavaScript: 82.6 KiB

#	Resource	Type	Size	Cache	Unused	3rd party	Issues

25 resources			692.7 KiB

Network Waterfall

25 requests over 11291ms

INFO

HTML JavaScript CSS Images Fonts XHR/Fetch Other

Third-Party Script Cost

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

INFO

54% of JavaScript execution is third-party

First-party Third-party 192ms · 101KB · $3/mo

Script	Category	Execution	Transfer	Unused	Monthly Cost	Verdict
Unattributable Unattributable	Other	121ms	0 KB	—	$2/mo	Optional
static.whatsapp.net static.whatsapp.net	Other	71ms	101 KB	51%	$1/mo	Optional

Unattributable

Other

Optional

Execution 121ms

Transfer 0 KB

Monthly Cost $2/mo

static.whatsapp.net

Other

Optional

Execution 71ms

Transfer 101 KB

Unused 51%

Monthly Cost $1/mo

54% 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

51% of static.whatsapp.net's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

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.