How would you go about investigating slow React application rendering?

0-2 years experience

1. 1You notice a single component takes noticeably longer to render after a state update. How would you start investigating the slowdown?
2. 2What built‑in tools would you use to measure render time in a small React project, and what would you look for?

2-5 years experience

1. 1Your team added a new list component and the page became sluggish. Walk me through how you'd debug the issue and decide whether to memoize parts of the list.
2. 2During a code review you see many components re‑rendering on every parent update. How would you identify the root cause and choose an appropriate optimization?

5-8 years experience

1. 1A large dashboard with dozens of widgets intermittently freezes. How would you design a profiling strategy and what architectural changes might you propose to improve rendering performance?
2. 2Explain how you would leverage React's Concurrent Mode or Suspense to mitigate rendering bottlenecks in a high‑traffic application.

8+ years experience

1. 1Your organization plans to migrate a legacy monolithic React app to a micro‑frontend architecture because of performance concerns. How would you approach the migration to minimize rendering latency across teams?
2. 2What long‑term monitoring and metrics would you put in place to ensure rendering performance stays within SLA across multiple services and releases?