How do you improve performance in a Node.js app?

Short answer: Use clustering or process managers like PM2 to utilize multiple CPU cores.

Explain a bit more

Implement caching (in-memory or distributed caches like Redis). Use asynchronous I/O properly (avoid blocking the event loop). Optimize database queries and use connection pooling. Minimize heavy computations in the main thread (offload with worker threads). Use gzip compression for responses. Properly manage memory leaks. Use load balancers in production.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.