The Challenge

When I took over the Trading Management System project, the initial page load was painfully slow at 4+ seconds. Users complained about poor responsiveness, and the Lighthouse performance score was stuck at 32.

The Investigation

Using Chrome DevTools and Lighthouse, I identified several bottlenecks:

• Large JavaScript bundle (450KB)
• Unnecessary re-renders across component tree
• Unoptimized images and third-party scripts
• Missing code splitting

The Solution

1. Code Splitting with Dynamic Imports

const ProjectCarousel = dynamic(() => import('@/components/ProjectCarousel'), {
  loading: () => <p>Loading...</p>,
  ssr: false
})

2. Strategic Memoization

const KeySkills = memo(() => {
  return <div>Skills...</div>
})

3. Image Optimization

Used Next.js Image component with blur placeholders and WebP format.

4. Bundle Analysis

Removed unused dependencies and optimized tree-shaking.

Results

• Initial Load Time: 4s → 1.2s (70% improvement)
• Lighthouse Performance: 32 → 89
• First Contentful Paint: 2.8s → 0.9s
• Cumulative Layout Shift: 0.15 → 0.02

Key Takeaways

1. Always profile before optimizing
2. Code splitting is your friend for large apps
3. Image optimization can provide 30-40% improvements
4. Monitor bundle size in CI/CD

Resources

• Next.js Performance: https://nextjs.org/learn/seo/performance
• React Performance: https://react.dev/reference/react/memo
• Lighthouse: https://developers.google.com/web/tools/lighthouse