How do I make a slow React page faster?

Definition:

Frontend performance includes initial loading, responsiveness during interaction and the cost of updating the UI. A slow page might be waiting for JavaScript, network data, layout or expensive component calculations. Profiling tells you which category matters before you make a targeted change.

Key points:

• Profile first; find costly renders, large bundles or slow network requests.

• Keep state local, virtualize long lists and split large features into lazy-loaded chunks.

• Add memoization only where it removes measured work.

• Virtualization reduces mounted rows, while pagination reduces fetched records; large lists may need both.

Interview point:

• Report the measured improvement in the relevant user action, not only the number of renders removed.