Context

Slow mobile rendering usually comes from a small number of bottlenecks: too much work on the main thread, expensive layout or drawing, or heavy data and image processing. Interviewers want to see whether you start with measurement and isolate the problem systematically.

Core Question

If a screen is slow to render on mobile, what would you look at first?

In your answer, explain:

1. What signals or metrics you would inspect before changing code.
2. How you would determine whether the issue is caused by data fetching, computation, layout, image work, or excessive re-renders.
3. What fixes you would prioritize first for the most common causes.

Scope Guidance

Focus on a practical debugging framework rather than platform-specific APIs. A strong answer should cover first principles: measure, identify the critical path, separate CPU/UI/network work, and prioritize the highest-impact optimizations.