SKILL.md
Performance Audit Skill
Analyze web page performance using Web Vitals and network timing metrics.
When to Use
This skill activates when:
- User asks about page performance or speed
- User wants to optimize load times
- User mentions slow page or poor user experience
- User needs Core Web Vitals metrics
- User asks about SEO performance factors
Capabilities
Web Vitals Analysis
- Get Core Web Vitals (
o11y_get-web-vitals)
- LCP (Largest Contentful Paint) - INP (Interaction to Next Paint) - CLS (Cumulative Layout Shift) - TTFB (Time to First Byte) - FCP (First Contentful Paint)
Network Performance
- Analyze request timing (
o11y_get-http-requests) - Identify slow API calls
- Check resource sizes
- Find blocking resources
Visual Analysis
- Capture page at different load stages
- Identify layout shifts visually
- Check above-the-fold content
JavaScript Analysis
- Profile JavaScript execution
- Check for long tasks
- Identify render-blocking scripts
Performance Thresholds
| Metric | Good | Needs Work | Poor |
|---|---|---|---|
| LCP | ≤2.5s | 2.5-4s | >4s |
| INP | ≤200ms | 200-500ms | >500ms |
| CLS | ≤0.1 | 0.1-0.25 | >0.25 |
| TTFB | ≤800ms | 800-1800ms | >1800ms |
Audit Workflow
- Baseline: Get initial Web Vitals metrics
- Network: Analyze slow/large requests
- Resources: Check for render-blocking resources
- JavaScript: Look for long tasks
- Images: Check for unoptimized images
- Report: Summarize with recommendations
Common Issues
- Large unoptimized images
- Render-blocking CSS/JS
- Too many HTTP requests
- Slow server response (TTFB)
- Layout shifts from dynamic content
- Uncompressed resources