Agent Skills
› tech-leads-club/agent-skills
› perf-web-optimization
perf-web-optimization
GitHub提供系统化的Web性能优化方案，涵盖图片、字体、第三方脚本及代码分割等关键领域。通过测量、识别、实施和验证流程，帮助解决加载缓慢、包体积过大及布局偏移问题，提升页面速度和用户体验。
Trigger Scenarios
网站加载速度慢
需要减小JS/CSS包体积
优化首屏渲染时间(LCP)
减少布局偏移(CLS)
实现懒加载或代码分割
Install
npx skills add tech-leads-club/agent-skills --skill perf-web-optimization -g -y
SKILL.md
Frontmatter
{
"name": "perf-web-optimization",
"description": "Optimize web performance: bundle size, images, caching, lazy loading, and overall page speed. Use when site is slow, reducing bundle size, fixing layout shifts, improving Time to Interactive, or optimizing for Lighthouse scores. Triggers on: web performance, bundle size, page speed, slow site, lazy loading. Do NOT use for Core Web Vitals-specific fixes (use core-web-vitals), running Lighthouse audits (use perf-lighthouse), or Astro-specific optimization (use perf-astro)."
}
Web Performance Optimization
Systematic approach: Measure → Identify → Prioritize → Implement → Verify.
Target Metrics
| 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 | 800ms-1.8s | > 1.8s |
Quick Wins
1. Images (usually biggest impact on LCP)
<!-- Hero/LCP image: eager + high priority -->
<img src="/hero.webp" alt="Hero" width="1200" height="600" loading="eager" fetchpriority="high" decoding="async" />
<!-- Below fold: lazy load -->
<img src="/product.webp" alt="Product" width="400" height="300" loading="lazy" decoding="async" />
Always set width and height to prevent CLS.
2. Fonts (common LCP/CLS culprit)
<!-- Preconnect to font origin -->
<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin />
<!-- Non-blocking font load -->
<link
rel="stylesheet"
href="https://fonts.googleapis.com/css2?family=Inter&display=swap"
media="print"
onload="this.media='all'"
/>
3. Third-party Scripts (common INP killer)
<!-- Defer to user interaction -->
<script>
function loadThirdParty() {
// Load analytics, chat widgets, etc.
}
;['scroll', 'click', 'touchstart'].forEach((e) => addEventListener(e, loadThirdParty, { once: true, passive: true }))
setTimeout(loadThirdParty, 5000)
</script>
4. Critical CSS
Inline critical CSS in <head>, defer the rest:
<style>
/* critical styles */
</style>
<link rel="preload" href="/styles.css" as="style" onload="this.rel='stylesheet'" />
Bundle Analysis
# Webpack
npx webpack-bundle-analyzer dist/stats.json
# Vite
npx vite-bundle-visualizer
# Check package size before installing
npx bundlephobia <package-name>
Common heavy packages to replace:
moment(67KB) →date-fns(12KB) ordayjs(2KB)lodash(72KB) → cherry-pick imports or native methods
Code Splitting Patterns
// React lazy
const Chart = lazy(() => import('./Chart'))
// Next.js dynamic
const Admin = dynamic(() => import('./Admin'), { ssr: false })
// Vite/Rollup manual chunks
build: {
rollupOptions: {
output: {
manualChunks: {
vendor: ['react', 'react-dom']
}
}
}
}
Caching Headers
# Static assets (immutable hash in filename)
Cache-Control: public, max-age=31536000, immutable
# HTML (revalidate)
Cache-Control: no-cache
# API responses
Cache-Control: private, max-age=0, must-revalidate
Measurement
For running audits, reading reports, and setting budgets, use the perf-lighthouse skill.
Checklist
Images
- Modern formats (WebP/AVIF)
- Responsive
srcset -
width/heightattributes -
loading="lazy"below fold -
fetchpriority="high"on LCP image
JavaScript
- Bundle < 200KB gzipped
- Code splitting by route
- Third-party scripts deferred
- No unused dependencies
CSS
- Critical CSS inlined
- Non-critical CSS deferred
- No unused CSS
Fonts
-
font-display: swap - Preconnect to font origin
- Subset if possible
Detailed Examples
For in-depth optimization patterns, see:
- references/core-web-vitals.md - Fixing LCP, CLS, INP issues
- references/bundle-optimization.md - Reducing JS bundle size
- references/image-optimization.md - Image formats, responsive images, sharp scripts
Version History
- 39e57ed Current 2026-07-25 05:43
