performance

Optimize web performance for faster loading and better user experience. Use when asked to "speed up my site", "optimize performance", "reduce load time", "fix slow loading", "improve page speed", or "performance audit".

Jump to install

Repository: davila7/claude-code-templates
Last source activity: January 31, 2026 at 21:32
Detected SKILL.md language: English
Stars: 30,229
Forks: 3,394

Install options

The review-first prompt is selected by default. You can switch to a direct command or download a local copy.

Install with Codex or Claude Copy this prompt, paste it into Codex, Claude, or another assistant, and let it review the skill page and install it for you.

A direct command skips the review prompt. Inspect the source before running it.

npx skills add https://github.com/davila7/claude-code-templates --skill performance

The command stays on one line. Scroll horizontally to inspect it before copying.

Prefer a local copy? Download the files currently available to SkillsMP.

Review the source files

Read SKILL.md and any companion files shown by SkillsMP before deciding whether to install.

SKILL.md

Source instructions · Read-only preview

Back to search Back to installation

computer-use-agents

Build AI agents that interact with computers like humans do - viewing screens, moving cursors, clicking buttons, and typing text. Covers Anthropic's Computer Use, OpenAI's Operator/CUA, and open-source alternatives. Critical focus on sandboxing, security, and handling the unique challenges of vision-based control. Use when: computer use, desktop automation agent, screen control AI, vision-based agent, GUI automation.

2026-08-04

ai-wrapper-product

Expert in building products that wrap AI APIs (OpenAI, Anthropic, etc.) into focused tools people will pay for. Not just 'ChatGPT but different' - products that solve specific problems with AI. Covers prompt engineering for products, cost management, rate limiting, and building defensible AI businesses. Use when: AI wrapper, GPT product, AI tool, wrap AI, AI SaaS.

2026-08-04

github-workflow-automation

Automate GitHub workflows with AI assistance. Includes PR reviews, issue triage, CI/CD integration, and Git operations. Use when automating GitHub workflows, setting up PR review automation, creating GitHub Actions, or triaging issues.

2026-08-04

View all from this repository

<link rel="preconnect" href="https://fonts.googleapis.com">
<link rel="preconnect" href="https://cdn.example.com" crossorigin>

<!-- LCP image -->
<link rel="preload" href="/hero.webp" as="image" fetchpriority="high">

<!-- Critical font -->
<link rel="preload" href="/font.woff2" as="font" type="font/woff2" crossorigin>

<!-- Critical CSS inlined -->
<style>/* Above-fold styles */</style>

<!-- Non-critical CSS -->
<link rel="preload" href="/styles.css" as="style" onload="this.onload=null;this.rel='stylesheet'">
<noscript><link rel="stylesheet" href="/styles.css"></noscript>

<!-- Parser-blocking (avoid) -->
<script src="/critical.js"></script>

<!-- Deferred (preferred) -->
<script defer src="/app.js"></script>

<!-- Async (for independent scripts) -->
<script async src="/analytics.js"></script>

<!-- Module (deferred by default) -->
<script type="module" src="/app.mjs"></script>

// Route-based splitting
const Dashboard = lazy(() => import('./Dashboard'));

// Component-based splitting
const HeavyChart = lazy(() => import('./HeavyChart'));

// Feature-based splitting
if (user.isPremium) {
  const PremiumFeatures = await import('./PremiumFeatures');
}

// ❌ Imports entire library
import _ from 'lodash';
_.debounce(fn, 300);

// ✅ Imports only what's needed
import debounce from 'lodash/debounce';
debounce(fn, 300);

<picture>
  <!-- AVIF for modern browsers -->
  <source 
    type="image/avif"
    srcset="hero-400.avif 400w,
            hero-800.avif 800w,
            hero-1200.avif 1200w"
    sizes="(max-width: 600px) 100vw, 50vw">
  
  <!-- WebP fallback -->
  <source 
    type="image/webp"
    srcset="hero-400.webp 400w,
            hero-800.webp 800w,
            hero-1200.webp 1200w"
    sizes="(max-width: 600px) 100vw, 50vw">
  
  <!-- JPEG fallback -->
  <img 
    src="hero-800.jpg"
    srcset="hero-400.jpg 400w,
            hero-800.jpg 800w,
            hero-1200.jpg 1200w"
    sizes="(max-width: 600px) 100vw, 50vw"
    width="1200" 
    height="600"
    alt="Hero image"
    loading="lazy"
    decoding="async">
</picture>

<!-- Above-fold LCP image: eager loading, high priority -->
<img 
  src="hero.webp" 
  fetchpriority="high"
  loading="eager"
  decoding="sync"
  alt="Hero">

<!-- Below-fold images: lazy loading -->
<img 
  src="product.webp" 
  loading="lazy"
  decoding="async"
  alt="Product">

/* System font stack as fallback */
body {
  font-family: 'Custom Font', -apple-system, BlinkMacSystemFont, 
               'Segoe UI', Roboto, sans-serif;
}

/* Prevent invisible text */
@font-face {
  font-family: 'Custom Font';
  src: url('/fonts/custom.woff2') format('woff2');
  font-display: swap; /* or optional for non-critical */
  font-weight: 400;
  font-style: normal;
  unicode-range: U+0000-00FF; /* Subset to Latin */
}

<link rel="preload" href="/fonts/heading.woff2" as="font" type="font/woff2" crossorigin>

/* One file instead of multiple weights */
@font-face {
  font-family: 'Inter';
  src: url('/fonts/Inter-Variable.woff2') format('woff2-variations');
  font-weight: 100 900;
  font-display: swap;
}

# HTML (short or no cache)
Cache-Control: no-cache, must-revalidate

# Static assets with hash (immutable)
Cache-Control: public, max-age=31536000, immutable

# Static assets without hash
Cache-Control: public, max-age=86400, stale-while-revalidate=604800

# API responses
Cache-Control: private, max-age=0, must-revalidate

// Cache-first for static assets
self.addEventListener('fetch', (event) => {
  if (event.request.destination === 'image' ||
      event.request.destination === 'style' ||
      event.request.destination === 'script') {
    event.respondWith(
      caches.match(event.request).then((cached) => {
        return cached || fetch(event.request).then((response) => {
          const clone = response.clone();
          caches.open('static-v1').then((cache) => cache.put(event.request, clone));
          return response;
        });
      })
    );
  }
});

// ❌ Forces multiple reflows
elements.forEach(el => {
  const height = el.offsetHeight; // Read
  el.style.height = height + 10 + 'px'; // Write
});

// ✅ Batch reads, then batch writes
const heights = elements.map(el => el.offsetHeight); // All reads
elements.forEach((el, i) => {
  el.style.height = heights[i] + 10 + 'px'; // All writes
});

function debounce(fn, delay) {
  let timeout;
  return (...args) => {
    clearTimeout(timeout);
    timeout = setTimeout(() => fn(...args), delay);
  };
}

// Debounce scroll/resize handlers
window.addEventListener('scroll', debounce(handleScroll, 100));

// ❌ May cause jank
setInterval(animate, 16);

// ✅ Synced with display refresh
function animate() {
  // Animation logic
  requestAnimationFrame(animate);
}
requestAnimationFrame(animate);

// For lists > 100 items, render only visible items
// Use libraries like react-window, vue-virtual-scroller, or native CSS:
.virtual-list {
  content-visibility: auto;
  contain-intrinsic-size: 0 50px; /* Estimated item height */
}

// ❌ Blocks main thread
<script src="https://analytics.example.com/script.js"></script>

// ✅ Async loading
<script async src="https://analytics.example.com/script.js"></script>

// ✅ Delay until interaction
<script>
document.addEventListener('DOMContentLoaded', () => {
  const observer = new IntersectionObserver((entries) => {
    if (entries[0].isIntersecting) {
      const script = document.createElement('script');
      script.src = 'https://widget.example.com/embed.js';
      document.body.appendChild(script);
      observer.disconnect();
    }
  });
  observer.observe(document.querySelector('#widget-container'));
});
</script>

<!-- Show static placeholder until interaction -->
<div class="youtube-facade" 
     data-video-id="abc123" 
     onclick="loadYouTube(this)">
  <img src="/thumbnails/abc123.jpg" alt="Video title">
  <button aria-label="Play video">▶</button>
</div>

# Lighthouse CLI
npx lighthouse https://example.com --output html --output-path report.html

# Web Vitals library
import {onLCP, onINP, onCLS} from 'web-vitals';
onLCP(console.log);
onINP(console.log);
onCLS(console.log);

name	performance
description	Optimize web performance for faster loading and better user experience. Use when asked to "speed up my site", "optimize performance", "reduce load time", "fix slow loading", "improve page speed", or "performance audit".
license	MIT
metadata	{"author":"web-quality-skills","version":"1.0"}

Resource	Budget	Rationale
Total page weight	< 1.5 MB	3G loads in ~4s
JavaScript (compressed)	< 300 KB	Parsing + execution time
CSS (compressed)	< 100 KB	Render blocking
Images (above-fold)	< 500 KB	LCP impact
Fonts	< 100 KB	FOIT/FOUT prevention
Third-party

name	performance
description	Optimize web performance for faster loading and better user experience. Use when asked to "speed up my site", "optimize performance", "reduce load time", "fix slow loading", "improve page speed", or "performance audit".
license	MIT
metadata	{"author":"web-quality-skills","version":"1.0"}

Resource	Budget	Rationale
Total page weight	< 1.5 MB	3G loads in ~4s
JavaScript (compressed)	< 300 KB	Parsing + execution time
CSS (compressed)	< 100 KB	Render blocking
Images (above-fold)	< 500 KB	LCP impact
Fonts	< 100 KB	FOIT/FOUT prevention
Third-party

Format	Use case	Browser support
AVIF	Photos, best compression	92%+
WebP	Photos, good fallback	97%+
PNG	Graphics with transparency	Universal
SVG	Icons, logos, illustrations	Universal

performance

Install options

Review the source files

Performance optimization

How it works

Performance budget

Performance optimization

How it works

Performance budget

Critical rendering path

Server response

Resource loading

JavaScript optimization

Image optimization

Format selection

Responsive images

LCP image priority

Font optimization

Loading strategy

Preloading critical fonts

Variable fonts

Caching strategy

Cache-Control headers

Service worker caching

Runtime performance

Avoid layout thrashing

Debounce expensive operations

Use requestAnimationFrame

Virtualize long lists

Third-party scripts

Load strategies

Facade pattern

Measurement

Key metrics

Testing commands

References

Metric	Target	Tool
LCP	< 2.5s	Lighthouse, CrUX
FCP	< 1.8s	Lighthouse
Speed Index	< 3.4s	Lighthouse
TBT	< 200ms	Lighthouse
TTI	< 3.8s	Lighthouse

performance

Source facts

Install options

Review the source files

More from this repository

More from this repository

Performance optimization

How it works

Performance budget

Performance optimization

How it works

Performance budget

Critical rendering path

Server response

Resource loading

JavaScript optimization

Image optimization

Format selection

Responsive images

LCP image priority

Font optimization

Loading strategy

Preloading critical fonts

Variable fonts

Caching strategy

Cache-Control headers

Service worker caching

Runtime performance

Avoid layout thrashing

Debounce expensive operations

Use requestAnimationFrame

Virtualize long lists

Third-party scripts

Load strategies

Facade pattern

Measurement

Key metrics

Testing commands

References