Agent skill
performance-audit
Run Lighthouse audit and verify Core Web Vitals. Use at project end before release. Triggers on "performance", "Lighthouse", "Core Web Vitals", "speed test", "page speed".
Install this agent skill to your Project
npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/testing/performance-audit-manuelvillarvieites-energy-company
SKILL.md
Performance Audit
Verify website performance meets Core Web Vitals standards.
Core Web Vitals Targets
| Metric | Target | What it measures |
|---|---|---|
| LCP | < 2.5s | Largest Contentful Paint (loading) |
| FID | < 100ms | First Input Delay (interactivity) |
| CLS | < 0.1 | Cumulative Layout Shift (stability) |
Audit Process
1. Run Lighthouse
# Using Chrome DevTools
# 1. Open site in Chrome
# 2. DevTools > Lighthouse tab
# 3. Run audit (Mobile + Desktop)
# Or CLI
npx lighthouse https://localhost:3000 --view
2. Check Results
Target Scores:
- Performance: > 90
- Accessibility: > 90
- Best Practices: > 90
- SEO: > 90
3. Common Issues & Fixes
LCP Issues:
- Add
priorityto above-fold images - Preload critical fonts
- Use Next.js Image component
- Enable image optimization
CLS Issues:
- Set explicit width/height on images
- Reserve space for dynamic content
- Avoid layout shifts from fonts
FID Issues:
- Minimize JavaScript bundle
- Use dynamic imports for heavy components
- Defer non-critical scripts
Checklist
Images:
- All images use WebP format
- Above-fold images have
priority - Images have width/height set
- Responsive images use
sizesprop
Fonts:
- Fonts loaded via next/font
- Font display: swap enabled
- No flash of unstyled text
JavaScript:
- No unused dependencies
- Dynamic imports for heavy components
- No render-blocking scripts
General:
- Lighthouse Performance > 90
- No console errors
- Mobile responsive
- HTTPS enabled
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