Optimize

Documentation Index

Fetch the complete documentation index at: https://mintlify.com/pbakaus/impeccable/llms.txt

Use this file to discover all available pages before exploring further.

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When to Use

• Improve page load times and Core Web Vitals scores
• Reduce JavaScript bundle size
• Fix slow animations or janky interactions
• Optimize images and assets
• Reduce layout thrashing and reflows
• Improve mobile performance
• Make the interface feel faster and more responsive

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Parameters

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Important Principle

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Workflow

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Optimization Strategies

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Loading Performance

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Optimize Images

• Use modern formats (WebP, AVIF)
• Proper sizing (don’t load 3000px image for 300px display)
• Lazy loading for below-fold images
• Responsive images (srcset, picture element)
• Compress images (80-85% quality is usually imperceptible)
• Use CDN for faster delivery

<img 
  src="hero.webp"
  srcset="hero-400.webp 400w, hero-800.webp 800w, hero-1200.webp 1200w"
  sizes="(max-width: 400px) 400px, (max-width: 800px) 800px, 1200px"
  loading="lazy"
  alt="Hero image"
/>

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Reduce JavaScript Bundle

• Code splitting (route-based, component-based)
• Tree shaking (remove unused code)
• Remove unused dependencies
• Lazy load non-critical code
• Use dynamic imports for large components

// Lazy load heavy component
const HeavyChart = lazy(() => import('./HeavyChart'));

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Optimize CSS

• Remove unused CSS
• Critical CSS inline, rest async
• Minimize CSS files
• Use CSS containment for independent regions

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Optimize Fonts

• Use font-display: swap or optional
• Subset fonts (only characters you need)
• Preload critical fonts
• Use system fonts when appropriate
• Limit font weights loaded

@font-face {
  font-family: 'CustomFont';
  src: url('/fonts/custom.woff2') format('woff2');
  font-display: swap; /* Show fallback immediately */
  unicode-range: U+0020-007F; /* Basic Latin only */
}

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Rendering Performance

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Avoid Layout Thrashing

// ❌ Bad: Alternating reads and writes (causes reflows)
elements.forEach(el => {
  const height = el.offsetHeight; // Read (forces layout)
  el.style.height = height * 2; // Write
});

// ✅ Good: Batch reads, then batch writes
const heights = elements.map(el => el.offsetHeight); // All reads
elements.forEach((el, i) => {
  el.style.height = heights[i] * 2; // All writes
});

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Optimize Rendering

• Use CSS contain property for independent regions
• Minimize DOM depth (flatter is faster)
• Reduce DOM size (fewer elements)
• Use content-visibility: auto for long lists
• Virtual scrolling for very long lists (react-window, react-virtualized)

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Reduce Paint & Composite

• Use transform and opacity for animations (GPU-accelerated)
• Avoid animating layout properties (width, height, top, left)
• Use will-change sparingly for known expensive operations
• Minimize paint areas (smaller is faster)

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Animation Performance

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GPU Acceleration

/* ✅ GPU-accelerated (fast) */
.animated {
  transform: translateX(100px);
  opacity: 0.5;
}

/* ❌ CPU-bound (slow) */
.animated {
  left: 100px;
  width: 300px;
}

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Smooth 60fps

• Target 16ms per frame (60fps)
• Use requestAnimationFrame for JS animations
• Debounce/throttle scroll handlers
• Use CSS animations when possible
• Avoid long-running JavaScript during animations

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Intersection Observer

// Efficiently detect when elements enter viewport
const observer = new IntersectionObserver((entries) => {
  entries.forEach(entry => {
    if (entry.isIntersecting) {
      // Element is visible, lazy load or animate
    }
  });
});

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React/Framework Optimization

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React-specific

• Use memo() for expensive components
• useMemo() and useCallback() for expensive computations
• Virtualize long lists
• Code split routes
• Avoid inline function creation in render
• Use React DevTools Profiler

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Framework-agnostic

• Minimize re-renders
• Debounce expensive operations
• Memoize computed values
• Lazy load routes and components

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Network Optimization

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Reduce Requests

• Combine small files
• Use SVG sprites for icons
• Inline small critical assets
• Remove unused third-party scripts

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Optimize APIs

• Use pagination (don’t load everything)
• GraphQL to request only needed fields
• Response compression (gzip, brotli)
• HTTP caching headers
• CDN for static assets

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Optimize for Slow Connections

• Adaptive loading based on connection (navigator.connection)
• Optimistic UI updates
• Request prioritization
• Progressive enhancement

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Core Web Vitals Optimization

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Largest Contentful Paint (LCP < 2.5s)

• Optimize hero images
• Inline critical CSS
• Preload key resources
• Use CDN
• Server-side rendering

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First Input Delay (FID < 100ms) / INP (< 200ms)

• Break up long tasks
• Defer non-critical JavaScript
• Use web workers for heavy computation
• Reduce JavaScript execution time

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Cumulative Layout Shift (CLS < 0.1)

• Set dimensions on images and videos
• Don’t inject content above existing content
• Use aspect-ratio CSS property
• Reserve space for ads/embeds
• Avoid animations that cause layout shifts

/* Reserve space for image */
.image-container {
  aspect-ratio: 16 / 9;
}

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Performance Monitoring

• Chrome DevTools (Lighthouse, Performance panel)
• WebPageTest
• Core Web Vitals (Chrome UX Report)
• Bundle analyzers (webpack-bundle-analyzer)
• Performance monitoring (Sentry, DataDog, New Relic)

• LCP, FID/INP, CLS (Core Web Vitals)
• Time to Interactive (TTI)
• First Contentful Paint (FCP)
• Total Blocking Time (TBT)
• Bundle size
• Request count

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Usage Example

# Optimize entire interface
/optimize

# Optimize specific feature
/optimize target="product gallery"

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Best Practices

• Measure before optimizing
• Test on real devices (especially low-end Android)
• Test with throttled connections (3G)
• Optimize the biggest bottleneck first
• Track real user monitoring data

• Optimize without measuring (premature optimization)
• Sacrifice accessibility for performance
• Break functionality while optimizing
• Use will-change everywhere (creates new layers, uses memory)
• Lazy load above-fold content
• Optimize micro-optimizations while ignoring major issues
• Forget about mobile performance (often slower devices, slower connections)

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Important Notes