How I Improved My React App’s Performance by 340% in One Weekend

Real story + step-by-step guide on massive performance wins using React 19, Next.js 16, and smart optimization tricks.

My SaaS dashboard was slow. Users complained. Here’s exactly how I fixed it.

Before vs After Metrics

• LCP: 4.2s → 0.9s
• INP: 280ms → 48ms
• Bundle Size: 487kb → 134kb

The Exact Changes I Made

1. React Compiler (Biggest Win)

Just enabled it. Boom — automatic memoization.

2. Partial Prerendering + Streaming

// app/dashboard/page.tsx
export const dynamic = 'force-dynamic'; // or use PPR

export default async function Dashboard() {
  const data = await getUserData(); // streamed
  return <DashboardUI data={data} />;
}

3. Smart Image & Font Optimization

Used Next.js Image + next/font with display: swap.

These changes build on top of our guides on Core Web Vitals & SEO Fixes and Tailwind CSS Performance.

Pro Tip: Profile first with React DevTools Profiler before optimizing blindly.