Inefficient List Rendering: Rendering large lists or complex components without?

Short answer: optimization can degrade performance, especially if each item is re-rendered every time the parent changes.

Real-world example (ShopNest)

When rendering cart lines, use a stable key={item.id}—not the array index—so React updates the right row after delete.

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.