Performance & Accessibility Optimization Summary

Performance & Accessibility Optimization Summary

Overview

This document summarizes the comprehensive performance and accessibility optimizations implemented for your Jekyll site based on PageSpeed Insights analysis.

Initial Score: Performance 62/100, Accessibility 85/100
Target Score: Performance 80-85/100, Accessibility 95+/100

✅ Implemented Optimizations

Performance Improvements

1. Deferred CSS Loading

  • External CSS now uses preload technique
  • Prevents render-blocking (~2,910ms savings)
  • Files: _includes/ext-css.html

2. Font Display Optimization

  • Added &display=swap to Google Fonts
  • Shows text immediately with fallback fonts
  • Files: _layouts/base.html

3. Deferred JavaScript

  • All JS files use defer attribute
  • Eliminates render-blocking scripts
  • Files: _includes/ext-js.html, _includes/footer-scripts.html

4. Resource Hints

  • Added preconnect/dns-prefetch for external domains
  • Speeds up connection establishment (~200-300ms)
  • Files: _includes/head.html

5. Image Optimization Support

  • Created responsive image component
  • Comprehensive optimization guide
  • Files: _includes/responsive-image.html, IMAGE_OPTIMIZATION.md

Accessibility Improvements

1. Color Contrast

  • Link colors: #0056b3 (7:1 ratio, exceeds WCAG AA)
  • Hover states: #003d82 (10.7:1 ratio)
  • Files: assets/css/accessibility.css

2. Touch Target Sizes

  • All interactive elements minimum 48×48px
  • 8px spacing between targets
  • Files: assets/css/accessibility.css

3. Keyboard Navigation

  • Skip-to-main-content link added
  • Enhanced focus indicators (3px outline + shadow)
  • Files: _includes/nav.html, _layouts/base.html
  • Underlines on hover/focus (2px thick)
  • Not relying on color alone
  • Files: assets/css/accessibility.css

5. ARIA Labels

  • Added aria-labels to icon-only links
  • Proper alt text for images
  • Width/height attributes prevent layout shift
  • Files: _includes/nav.html

6. Semantic HTML

  • Content wrapped in <main> landmark
  • Proper heading hierarchy
  • Files: _layouts/base.html

📁 Files Modified

_includes/
  ├── ext-css.html          [Deferred CSS loading]
  ├── ext-js.html           [Deferred JS loading]
  ├── footer-scripts.html   [Deferred JS loading]
  ├── head.html             [Resource hints]
  ├── nav.html              [Skip link, ARIA labels, image dimensions]
  └── responsive-image.html [NEW: Image component]

_layouts/
  └── base.html             [Font display, accessibility CSS, main landmark]

assets/css/
  └── accessibility.css     [NEW: Comprehensive a11y styles]

Documentation:
  ├── PERFORMANCE.md        [NEW: Performance guide]
  ├── ACCESSIBILITY.md      [NEW: Accessibility guide]
  ├── IMAGE_OPTIMIZATION.md [NEW: Image optimization guide]
  └── OPTIMIZATION_SUMMARY.md [THIS FILE]

🚀 Expected Improvements

Metric Before Expected After Improvement
Performance Score 62 80-85 +18-23
Accessibility Score 85 95+ +10+
First Contentful Paint 5.0s 2.5-3.0s -2.0-2.5s
Largest Contentful Paint 7.9s 4.0-5.0s -2.9-3.9s
Total Blocking Time 90ms 30-50ms -40-60ms
Speed Index 5.6s 3.5-4.0s -1.6-2.1s
Cumulative Layout Shift 0 0 ✅ Maintained

🧪 Testing Steps

Local Testing

  1. Start Jekyll server: 
    cd /home/heaohan/Projects/heaohan.github.io
bundle exec jekyll serve
  2. Open Chrome DevTools (F12):
    • Lighthouse Tab: Run Performance + Accessibility audit
    • Network Tab: Verify defer/preload attributes
    • Coverage Tab: Check unused CSS/JS
  3. Test Accessibility:
    • Tab through all interactive elements
    • Verify focus indicators are visible
    • Test skip-to-main link (press Tab once)
    • Check color contrast in Elements tab
  4. Mobile Testing:
    • Toggle Device Toolbar (Ctrl+Shift+M)
    • Select “Moto G Power” or similar
    • Test touch target sizes
    • Verify responsive layout

Deployment Testing

  1. Commit and push: 
    git add .
git commit -m "feat: implement performance and accessibility optimizations"
git push origin master

  2. Wait for GitHub Pages (2-5 minutes)

  3. Run PageSpeed Insights: 
    https://pagespeed.web.dev/analysis/https-heaohan-github-io/
  4. Verify improvements:
    • Performance score should be 80+
    • Accessibility score should be 95+
    • All Core Web Vitals in green

📝 Next Steps (Optional)

Priority 1: Image Optimization

Follow IMAGE_OPTIMIZATION.md:

cd assets/img
# Optimize avatar
convert mylogo.jpg -resize 200x200\> -quality 85 mylogo-opt.jpg
convert mylogo.jpg -quality 85 mylogo.webp

Update _config.yml:

avatar: "/assets/img/mylogo-opt.jpg"

Priority 2: Minification

Add to _config.yml:

sass:
  style: compressed

compress_html:
  clippings: all
  comments: all
  endings: all

Priority 3: Service Worker

Implement offline support (see PERFORMANCE.md)

Priority 4: CDN

Consider Cloudflare or Netlify for:

  • Better caching control
  • Image optimization
  • HTTP/3 support
  • Geographic distribution

🔍 Monitoring

Continuous Monitoring

  1. Weekly PageSpeed checks: Track performance trends
  2. Google Search Console: Monitor Core Web Vitals
  3. Browser DevTools: Local performance testing

Key Metrics to Watch

  • Largest Contentful Paint < 2.5s
  • First Input Delay < 100ms
  • Cumulative Layout Shift < 0.1
  • Accessibility Score > 95

🛠️ Troubleshooting

Issue: CSS Doesn’t Load

Symptom: Page appears unstyled
Solution: Check browser console, ensure JavaScript enabled

Issue: JavaScript Errors

Symptom: Interactive features broken
Solution: Some scripts may need specific load order. Move critical scripts to <head> without defer

Issue: Focus Indicators Too Prominent

Symptom: Blue outline on all interactions
Solution: This is intentional for accessibility. Do not remove.

Issue: Fonts Flash

Symptom: Text changes appearance after loading
Solution: This is expected with font-display: swap. Consider preloading fonts:

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

📚 Documentation

  • PERFORMANCE.md: Detailed performance guide with explanations
  • ACCESSIBILITY.md: WCAG 2.1 compliance details and testing
  • IMAGE_OPTIMIZATION.md: Image compression and optimization workflow

✨ Summary

What Was Optimized

✅ Render-blocking resources eliminated
✅ Font loading optimized
✅ JavaScript execution deferred
✅ External connections pre-established
✅ Color contrast improved (WCAG AA)
✅ Touch targets enlarged (48×48px minimum)
✅ Keyboard navigation enhanced
✅ Screen reader support improved
✅ Layout shift prevented

What’s Still Needed (Manual)

⚠️ Optimize images (convert to WebP, compress)
⚠️ Enable HTML/CSS minification
⚠️ Consider CDN for static assets

Quick Win Checklist

  • Test locally with Lighthouse
  • Verify keyboard navigation works
  • Check mobile touch targets
  • Deploy to GitHub Pages
  • Re-test with PageSpeed Insights
  • Document before/after scores
  • Optimize images (see guide)
  • Enable minification

🎯 Success Criteria

Your site will be considered optimized when:

  • ✅ Performance score ≥ 80
  • ✅ Accessibility score ≥ 95
  • ✅ All Core Web Vitals in “Good” range
  • ✅ No WCAG AA violations
  • ✅ Mobile usability 100%

Date Implemented: December 7, 2025
PageSpeed Report: https://pagespeed.web.dev/analysis/https-heaohan-github-io/yz8lf7fhk7?form_factor=mobile

For questions or issues, refer to the detailed guides in:

  • PERFORMANCE.md
  • ACCESSIBILITY.md
  • IMAGE_OPTIMIZATION.md