Measuring and Improving Performance with Lighthouse #

1. Running a Lighthouse Audit #

Google’s Lighthouse tool evaluates:

• Performance → Speed, asset loading, lazy loading.
• SEO → Indexability, metadata, structured data.
• PWA compliance → Installability, service worker usage.

Run a Lighthouse audit in Chrome DevTools:

• Open DevTools (F12) → Lighthouse Tab.
• Select Performance, PWA, SEO.
• Click "Generate Report".

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2. Analyzing Lighthouse Scores #

Your score will be rated out of 100 for:

• ✅ Performance (aim for 90+)
• ✅ SEO (aim for 100)
• ✅ PWA compliance (must be 100)

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3. Fixing Common Lighthouse Issues #

• ✅ "Reduce Unused JavaScript" → Tree-shake your JavaScript files in Webpack.
• ✅ "Eliminate Render-Blocking Resources" → Use async and defer for JavaScript:
  • <script src="application.js" defer></script>
• ✅ "Serve Images in Next-Gen Formats" → Use WebP instead of PNG/JPG:
  • <picture> <source srcset="image.webp" type="image/webp"> <img src="image.jpg" alt="Fallback"> </picture>
• ✅ "Minimize Main Thread Work" → Move long JavaScript calculations to a Web Worker.

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4. Using PageSpeed Insights for Live Monitoring #

Use PageSpeed Insights to get real-time performance feedback.

• 📱 Check mobile and desktop performance separately.
• 📉 Identify bottlenecks that slow down the PWA.
• 🛠 Get Google’s recommendations on optimizations.

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By following these strategies, your Rails PWA will load faster, rank higher in Google, and provide an optimized experience across all devices.