astro-performance
Installation
SKILL.md
Astro Performance Skill
Purpose
Achieve 90+ Lighthouse mobile scores and pass Core Web Vitals on every page. Direct impact on SEO rankings, crawl priority, and conversion rates.
Core Web Vitals Targets
| Metric | Good | Needs Improvement | Poor |
|---|---|---|---|
| LCP (Largest Contentful Paint) | ≤2.5s | 2.5–4s | >4s |
| INP (Interaction to Next Paint) | ≤200ms | 200–500ms | >500ms |
| CLS (Cumulative Layout Shift) | ≤0.1 | 0.1–0.25 | >0.25 |
Critical Path Rule
The critical rendering path must be max 3 hops: HTML → CSS → LCP image.
Anything that adds a 4th hop (font in CSS chain, extra CSS file, unpreloaded image) adds 150–500ms to LCP on mobile. This is the #1 cause of poor mobile scores.