perf-astro
perf-astro is an Astro-specific skill for achieving 95+ Lighthouse scores through critical CSS inlining, compression, font loading optimization, and largest contentful paint (LCP) improvements. Use this skill when optimizing Astro site performance metrics, configuring astro-critters and compression integrations, or implementing above-the-fold CSS extraction and minification strategies for Astro projects.
git clone --depth 1 https://github.com/tech-leads-club/agent-skills /tmp/perf-astro && cp -r /tmp/perf-astro/packages/skills-catalog/skills/(performance)/perf-astro ~/.claude/skills/perf-astroSKILL.md
# Astro Performance Playbook
Astro-specific optimizations for 95+ Lighthouse scores.
## Quick Setup
```bash
npm install astro-critters @playform/compress
```
```js
// astro.config.mjs
import { defineConfig } from 'astro/config'
import critters from 'astro-critters'
import compress from '@playform/compress'
export default defineConfig({
integrations: [
critters(),
compress({
CSS: true,
HTML: true,
JavaScript: true,
Image: false,
SVG: false,
}),
],
})
```
## Integrations
### astro-critters
Automatically extracts and inlines critical CSS. No configuration needed.
What it does:
- Scans rendered HTML for above-the-fold elements
- Inlines only the CSS those elements need
- Lazy-loads the rest
Build output shows what it inlined:
```
Inlined 40.70 kB (80% of original 50.50 kB) of _astro/index.xxx.css.
```
### @playform/compress
Minifies HTML, CSS, and JavaScript in the final build.
Options:
```js
compress({
CSS: true, // Minify CSS
HTML: true, // Minify HTML
JavaScript: true, // Minify JS
Image: false, // Skip if using external image optimization
SVG: false, // Skip if SVGs are already optimized
})
```
## Layout Pattern
Structure your `Layout.astro` for performance:
```astro
---
import '../styles/global.css'
---
<!doctype html>
<html lang="pt-BR">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<!-- Font fallback (prevents FOIT) -->
<style>
@font-face {
font-family: 'Inter';
font-display: swap;
src: local('Inter');
}
</style>
<!-- Non-blocking Google Fonts -->
<link rel="preconnect" href="https://fonts.googleapis.com">
<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
<link
rel="stylesheet"
href="https://fonts.googleapis.com/css2?family=Inter:wght@400;600;700&display=swap"
media="print"
onload="this.media='all'"
/>
<noscript>
<link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Inter:wght@400;600;700&display=swap">
</noscript>
<!-- Preload LCP images -->
<link rel="preload" as="image" href="/hero.png" fetchpriority="high">
<title>{title}</title>
<!-- Defer third-party scripts -->
<script>
let loaded = false;
function loadAnalytics() {
if (loaded) return;
loaded = true;
// Load GTM, analytics, etc.
}
['scroll', 'click', 'touchstart'].forEach(e => {
document.addEventListener(e, loadAnalytics, { once: true, passive: true });
});
setTimeout(loadAnalytics, 5000);
</script>
</head>
<body>
<slot />
</body>
</html>
```
## Measuring
```bash
npx lighthouse https://your-site.com --preset=perf --form-factor=mobile
```
See also:
- **perf-lighthouse** - Running audits, reading reports, setting budgets
- **perf-web-optimization** - Core Web Vitals, bundle size, caching strategies
## Checklist
- [ ] `astro-critters` installed and configured
- [ ] `@playform/compress` installed and configured
- [ ] Google Fonts use `media="print" onload` pattern
- [ ] Third-party scripts deferred to user interaction
- [ ] LCP images preloaded in `<head>`Finds duplicate business logic spread across multiple components and suggests consolidation. Use when asking "where is this logic duplicated?", "find common code between services", "what can be consolidated?", "detect shared domain logic", or analyzing component overlap before refactoring. Do NOT use for code-level duplication detection (use linters) or dependency analysis (use coupling-analysis).
Detects misplaced classes and fixes component hierarchy problems — finds code that should belong inside a component but sits at the root level. Use when asking "clean up component structure", "find orphaned classes", "fix module hierarchy", "flatten nested components", or analyzing why namespaces have misplaced code. Do NOT use for dependency analysis (use coupling-analysis) or domain grouping (use domain-identification-grouping).
Maps architectural components in a codebase and measures their size to identify what should be extracted first. Use when asking "how big is each module?", "what components do I have?", "which service is too large?", "analyze codebase structure", "size my monolith", or planning where to start decomposing. Do NOT use for runtime performance sizing or infrastructure capacity planning.
Analyzes coupling between modules using the three-dimensional model (strength, distance, volatility) from "Balancing Coupling in Software Design". Use when asking "are these modules too coupled?", "show me dependencies", "analyze integration quality", "which modules should I decouple?", "coupling report", or evaluating architectural health. Do NOT use for domain boundary analysis (use domain-analysis) or component sizing (use component-identification-sizing).
Creates step-by-step decomposition plans and migration roadmaps for breaking apart monolithic applications. Use when asking "what order should I extract services?", "plan my migration", "create a decomposition roadmap", "prioritize what to split", "monolith to microservices strategy", or tracking decomposition progress. Do NOT use for domain analysis (use domain-analysis) or component sizing (use component-identification-sizing).
Maps business domains and suggests service boundaries in any codebase using DDD Strategic Design. Use when asking "what are the domains in this codebase?", "where should I draw service boundaries?", "identify bounded contexts", "classify subdomains", "DDD analysis", or analyzing domain cohesion. Do NOT use for grouping existing components into domains (use domain-identification-grouping) or dependency analysis (use coupling-analysis).
Groups existing components into logical business domains to plan service-based architecture. Use when asking "which components belong together?", "group these into services", "organize by domain", "component-to-domain mapping", or planning service extraction from an existing codebase. Do NOT use for identifying new domains from scratch (use domain-analysis) or analyzing coupling (use coupling-analysis).
AI frontend specialist and design consultant that guides users through a structured discovery process before generating any code. Collects visual references, design tokens, typography, icons, layout preferences, and brand guidelines to ensure the final output matches the user's vision with high fidelity. Use when the user asks to build, design, create, or improve any frontend interface — websites, landing pages, dashboards, components, apps, emails, forms, modals, or any UI element. Also triggers on "build me a UI", "design a page", "create a component", "improve this layout", "make this look better", "frontend", "interface", "redesign", or when the user provides mockups, screenshots, or design references. Do NOT use for backend logic, API design, database schemas, or non-visual code tasks.