Audit Checklist

40-Point Performance Audit

Systematically audit every Core Web Vital. Check off items as you fix them and track your score in real time.

Set fetchpriority="high" on the LCP image element

LCPhigh

LCPhigh

Serve images in WebP or AVIF format

LCPhigh

Enable a CDN for static assets (Cloudflare, Vercel, CloudFront)

LCPhigh

Server response time (TTFB) is under 600ms

LCPmedium

Provide srcset and sizes on all images

LCPmedium

Compress and resize images to appropriate max width

LCPmedium

Use stale-while-revalidate caching on HTML responses

LCPmedium

Inline critical CSS (above-the-fold styles)

LCPlow

Remove render-blocking stylesheets and scripts

LCPlow

No JavaScript task exceeds 50ms (break up long tasks)

INPhigh

Debounce high-frequency event handlers (input, scroll, resize)

INPhigh

Defer non-critical scripts with defer or async attributes

INPhigh

Move heavy computation to Web Workers

INPmedium

Use scheduler.postTask() or scheduler.yield() for background work

INPmedium

Virtualise long lists (react-window, TanStack Virtual)

INPmedium

Avoid layout thrash (batch DOM reads/writes)

INPmedium

Profile and remove unused JavaScript with bundle analyser

INPlow

Use code-splitting / dynamic imports for routes and heavy modules

INPlow

Enable tree-shaking in your bundler config

INPlow

All <img> elements have explicit width and height attributes

CLShigh

All ad slots and embeds have a reserved min-height

CLShigh

Font swap does not cause layout shift (use size-adjust fallback)

CLShigh

Dynamic banners/toasts are inserted above existing content, not injected mid-flow

CLShigh

Animations use transform and opacity only (not top/left/width/height)

CLSmedium

Sticky or fixed positioned elements do not cause reflow on scroll

CLSmedium

Skeleton loading screens replace empty states during data fetch

CLSmedium

Video embeds have aspect-ratio CSS property set

CLSlow

CSS transitions use will-change sparingly and correctly

CLSlow

No content is injected above the fold after page load

CLSlow

Tested on real device (Android mid-range) with throttling

Generalhigh

PageSpeed Insights score ≥ 90 on mobile

Generalhigh

HTTPS enabled with valid certificate

Generalmedium

HTTP/2 or HTTP/3 enabled on hosting provider

Generalmedium

Gzip or Brotli compression enabled on server

Generalmedium

Third-party scripts loaded with async, defer, or facade pattern

Generalmedium

Resource Hints: dns-prefetch and preconnect for critical origins

Generallow

Lighthouse CI integrated into your CI/CD pipeline

Generallow

CrUX data monitored in Search Console

Generallow

Performance budget set and documented in project

Generallow

Your Score

0 / 40 completed

Needs Work0–49%

Getting There50–79%

Excellent80–100%

🔧 Lots to improve