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Performance Optimization Guide

Overview

This document outlines all performance optimizations implemented in the SAVIGN website and provides guidelines for maintaining optimal performance.

Performance Targets

Core Web Vitals

  • First Contentful Paint (FCP): < 1.5s
  • Largest Contentful Paint (LCP): < 2.5s
  • Time to Interactive (TTI): < 3.5s
  • Cumulative Layout Shift (CLS): < 0.1
  • First Input Delay (FID): < 100ms

File Size Budgets

  • Total Page Weight: < 500KB (initial load)
  • HTML: < 50KB
  • CSS: < 50KB (minified)
  • JavaScript: < 100KB (minified)
  • Images: < 200KB per hero image, < 100KB per content image

Implemented Optimizations

1. Image Optimization

WebP Format with Fallbacks

<picture>
  <source srcset="image.webp" type="image/webp">
  <source srcset="image.jpg" type="image/jpeg">
  <img src="image.jpg" alt="Description" loading="lazy">
</picture>

Benefits:

  • WebP provides 25-35% better compression than JPEG
  • Fallback ensures compatibility with all browsers
  • Lazy loading reduces initial page weight

Responsive Images

<picture>
  <source srcset="image-small.webp 400w,
                  image-medium.webp 800w,
                  image-large.webp 1200w"
          type="image/webp"
          sizes="(max-width: 768px) 100vw, 50vw">
  <img src="image-medium.jpg" alt="Description" loading="lazy">
</picture>

Benefits:

  • Serves appropriately sized images for each device
  • Reduces bandwidth usage on mobile devices
  • Improves load times

Lazy Loading

  • All below-the-fold images use loading="lazy"
  • Above-the-fold images load immediately
  • Reduces initial page weight by 40-60%

Implementation: See assets/images/README.md for detailed guidelines

2. CSS Optimization

Critical CSS Inlining

Critical above-the-fold CSS is inlined in <head>:

  • Header/navigation styles
  • Hero section styles
  • Essential reset and variables
  • Critical responsive breakpoints

Benefits:

  • Eliminates render-blocking CSS requests
  • Faster First Contentful Paint
  • Improved perceived performance

Async CSS Loading

Non-critical CSS loads asynchronously:

<link rel="preload" href="./css/components.css" as="style" 
      onload="this.onload=null;this.rel='stylesheet'">

Benefits:

  • Doesn't block page rendering
  • Progressive enhancement
  • Faster Time to Interactive

CSS Minification

Production CSS is minified:

  • Removes comments and whitespace
  • Reduces file size by 30-40%
  • Faster download and parse times

Build Command:

./build-css.sh

Relative Units

All sizing uses relative units:

  • rem for consistent scaling
  • em for component-relative sizing
  • vw/vh for viewport-relative sizing
  • clamp() for fluid typography

Benefits:

  • Better responsive behavior
  • Accessibility (respects user font size preferences)
  • Smaller CSS file size

Implementation: See css/README.md for detailed guidelines

3. JavaScript Optimization

Deferred Script Loading

All scripts use defer attribute:

<script src="./js/main.js" defer></script>

Benefits:

  • Scripts don't block HTML parsing
  • Execute after DOM is ready
  • Maintains execution order
  • Faster page load

Debouncing & Throttling

Resize and scroll events are optimized:

Debouncing (resize events):

const handleResize = debounce(() => {
  // Runs 150ms after resize stops
}, 150);

Throttling (scroll events):

const handleScroll = throttle(() => {
  // Runs at most once per 100ms
}, 100);

Benefits:

  • Reduces function calls by 90%+
  • Prevents performance bottlenecks
  • Smoother scrolling and resizing

Event Delegation

Single event listener on parent instead of multiple listeners:

// One listener handles all menu links
menuOverlay.addEventListener('click', (e) => {
  if (e.target.classList.contains('menu-link')) {
    close();
  }
});

Benefits:

  • Fewer event listeners = less memory
  • Better performance
  • Works with dynamic content

Intersection Observer

Scroll animations use Intersection Observer instead of scroll events:

const observer = new IntersectionObserver(callback, options);
observer.observe(element);

Benefits:

  • More efficient than scroll listeners
  • Automatic viewport calculations
  • Better battery life on mobile

JavaScript Minification

Production JavaScript is minified:

  • Removes comments and whitespace
  • Shortens variable names
  • Reduces file size by 40-50%

Build Command:

./build-js.sh

Implementation: See js/README.md for detailed guidelines

4. Animation Performance

GPU-Accelerated Properties

All animations use only transform and opacity:

.element {
  transition: transform 0.3s ease, opacity 0.3s ease;
}

.element:hover {
  transform: scale(1.02);
  opacity: 0.9;
}

Benefits:

  • GPU acceleration
  • 60fps animations
  • No layout thrashing

Reduced Motion Support

Respects user preferences:

@media (prefers-reduced-motion: reduce) {
  * {
    animation: none !important;
    transition: none !important;
  }
}

Benefits:

  • Accessibility compliance
  • Better experience for users with motion sensitivity
  • Improved performance on low-end devices

5. Network Optimization

Resource Hints

<link rel="preload" href="./css/main.css" as="style">
<link rel="dns-prefetch" href="https://fonts.googleapis.com">

Benefits:

  • Faster resource loading
  • Reduced latency
  • Better perceived performance

Compression

Enable gzip/brotli compression on server:

# .htaccess (Apache)
<IfModule mod_deflate.c>
  AddOutputFilterByType DEFLATE text/html text/css text/javascript
</IfModule>

Benefits:

  • 70-80% file size reduction
  • Faster downloads
  • Lower bandwidth costs

Build Process

Development Build

Use unminified files for easier debugging:

# No build needed, use source files directly

Production Build

Build optimized files for deployment:

# Build everything
./build.sh

# Or build individually
./build-css.sh
./build-js.sh

Deployment

  1. Run production build
  2. Use index.prod.html or update index.html to use minified files
  3. Deploy all files including css/dist/ and js/dist/
  4. Enable compression on server
  5. Set appropriate cache headers

Performance Testing

Tools

Lighthouse

# Install
npm install -g lighthouse

# Run audit
lighthouse http://localhost:8000 --view

Targets:

  • Performance: > 90
  • Accessibility: > 90
  • Best Practices: > 90
  • SEO: > 90

WebPageTest

Chrome DevTools

Performance Tab:

  1. Open DevTools (F12)
  2. Go to Performance tab
  3. Click Record
  4. Interact with page
  5. Stop recording
  6. Analyze timeline

Coverage Tab:

  1. Open DevTools (F12)
  2. Press Cmd+Shift+P (Mac) or Ctrl+Shift+P (Windows)
  3. Type "Coverage"
  4. Click "Start instrumenting coverage"
  5. Reload page
  6. Identify unused CSS/JS

Network Tab:

  1. Open DevTools (F12)
  2. Go to Network tab
  3. Reload page
  4. Check file sizes and load times
  5. Test with throttling (Slow 3G, Fast 3G)

Performance Checklist

Before Deployment

  • Run Lighthouse audit (score > 90)
  • Test on slow 3G connection
  • Test on low-end mobile device
  • Verify all images are optimized
  • Verify CSS is minified
  • Verify JavaScript is minified
  • Check for console errors
  • Test all interactive features
  • Verify lazy loading works
  • Check Core Web Vitals

After Deployment

  • Run Lighthouse on live site
  • Test from multiple locations
  • Monitor real user metrics
  • Check server compression
  • Verify cache headers
  • Test on various devices/browsers

Monitoring

Real User Monitoring (RUM)

Consider implementing:

  • Google Analytics 4 (Web Vitals)
  • Cloudflare Web Analytics
  • Vercel Analytics
  • Custom performance tracking

Synthetic Monitoring

Set up automated testing:

  • Lighthouse CI
  • WebPageTest API
  • Pingdom
  • UptimeRobot

Optimization Opportunities

Future Improvements

1. HTTP/2 Server Push

Push critical resources before browser requests them

2. Service Worker

Cache assets for offline access and faster repeat visits

3. Code Splitting

Split JavaScript into smaller chunks loaded on demand

4. Tree Shaking

Remove unused code from JavaScript bundles

5. Image CDN

Use CDN with automatic optimization (Cloudinary, Imgix)

6. Font Optimization

  • Use variable fonts
  • Subset fonts to include only needed characters
  • Use font-display: swap

7. Preconnect to Third-Party Origins

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

Performance Budget

Enforcement

Set up performance budgets in build process:

{
  "budgets": [
    {
      "resourceSizes": [
        { "resourceType": "script", "budget": 100 },
        { "resourceType": "stylesheet", "budget": 50 },
        { "resourceType": "image", "budget": 200 }
      ]
    }
  ]
}

Monitoring

  • Fail builds that exceed budget
  • Alert team when approaching limits
  • Regular performance reviews

Best Practices

Do's

✅ Optimize images before adding to site ✅ Use lazy loading for below-fold content ✅ Minify CSS and JavaScript for production ✅ Use relative units for responsive design ✅ Debounce/throttle event handlers ✅ Use GPU-accelerated animations ✅ Test on real devices ✅ Monitor performance metrics

Don'ts

❌ Don't add images without optimization ❌ Don't use large JavaScript libraries unnecessarily ❌ Don't animate layout properties (width, height, top, left) ❌ Don't use inline styles (except critical CSS) ❌ Don't ignore console warnings ❌ Don't skip performance testing ❌ Don't deploy without minification

Resources

Documentation

Tools

Optimization Guides

Support

For questions or issues related to performance optimization, please refer to:

  • assets/images/README.md - Image optimization
  • css/README.md - CSS optimization
  • js/README.md - JavaScript optimization