My React App Seemed Fine Until I Scanned It

As a React developer with over 5 years of experience, I’ve always made performance a priority. My components were optimized. There were no console errors or warnings. Lighthouse even gave me a score of 92.

Still, I kept facing issues:

• ❌ Slow initial load times
• ❌ Inconsistent re-renders
• ❌ Feedback from users: “It feels a bit laggy…”

So one evening, I decided to try a tool I hadn’t used before:

npx react-scan .

react-scan a CLI tool that uncovers real React performance issues. It detects:

• ✅ Unnecessary re-renders
• ✅ Incorrect usage of memo, useCallback, and useMemo
• ✅ Leaky or redundant props
• ✅ Subtle anti-patterns most linters miss

To my surprise, it found 12 genuine performance flaws I had completely overlooked.

What I Fixed:

• 4 props that were breaking memoization
• 3 objects recreated on every render
• 1 useEffect missing a dependency
• 2 unused useCallback functions
• 1 rogue console.log running 80 times per second 😅

💡 5 Practical Tips to Improve React Performance

1. Avoid inline arrow functions in props Use useCallback to reduce unnecessary re-renders.

2. Virtualize large lists Libraries like react-window help maintain a healthy DOM.

3. Don’t overuse React.memo Memoization isn’t always the solution use it thoughtfully.

4. Use useMemo for stable object references Prevents re-renders in children caused by shallow comparison.

5. Split large components into smaller ones Smaller components are faster, cleaner, and easier to test.

🚀 Get Started

Install the tool globally:

npm install -g react-scan

Then run it:

react-scan .

No configuration needed just actionable results.

Final Thought

Assuming your app is fast isn’t enough. Measure it. Prove it.

This tool gave me a new perspective on performance. Try it once if it finds nothing, send me a message. I’ll buy you a coffee ☕.

#ReactJS #Performance #DevTools #ReactScan #WebDev #FrontendTips #CodeQuality #CleanCode #Debugging