Optimize Astro sites to achieve 95+ Lighthouse scores. Automatically manages CSS, HTML, and JS minification.

Install

mkdir -p .claude/skills/perf-astro && curl -L -o skill.zip "https://agentskills.codes/api/skills/download/1155" && unzip -o skill.zip -d .claude/skills/perf-astro && rm skill.zip

Installs to .claude/skills/perf-astro

Activation

This is the description your AI agent reads to decide when to run this skill — the better it matches your request, the more reliably it fires.

Astro-specific performance optimizations for 95+ Lighthouse scores. Covers critical CSS inlining, compression, font loading, and LCP optimization. Use when optimizing Astro site performance, improving Astro Lighthouse scores, or configuring astro-critters. Do NOT use for non-Astro sites (use perf-web-optimization or core-web-vitals) or running Lighthouse audits (use perf-lighthouse).
386 chars✓ has a “when” triggerlonger than Claude Code's old 250-char listing cap (fine on current versions)
Intermediate

Key capabilities

  • Extract and inline critical CSS using astro-critters
  • Minify HTML, CSS, and JavaScript with @playform/compress
  • Implement font loading with media print and onload patterns
  • Defer third-party scripts until user interaction
  • Preload LCP images with high fetchpriority

How it works

It integrates astro-critters to inline critical CSS and @playform/compress to minify build assets. It also provides a layout pattern for font loading and script deferral to improve performance metrics.

Inputs & outputs

You give it
Astro project source code
You get back
Optimized build assets with high Lighthouse performance scores

When to use perf-astro

  • Optimizing Astro site performance
  • Improving Google Lighthouse scores
  • Automating critical CSS inlining

About this skill

Astro Performance Playbook

Astro-specific optimizations for 95+ Lighthouse scores.

Quick Setup

npm install astro-critters @playform/compress
// 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:

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:

---
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

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>

When not to use it

  • Non-Astro sites
  • Running Lighthouse audits

Prerequisites

astro-critters@playform/compress

Limitations

  • Requires manual configuration of astro.config.mjs
  • Does not automate Lighthouse audit execution

How it compares

Unlike manual optimization, this skill provides a pre-configured integration set specifically for the Astro build lifecycle.

Compared to similar skills

perf-astro side by side with the closest alternatives in the catalog.

SkillInstallsUpdatedSafetyDifficulty
perf-astro (this skill)35moReviewIntermediate
nextjs-developer3282moNo flagsAdvanced
frontend-developer274moNo flagsIntermediate
senior-frontend157moReviewIntermediate

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