"Tell me about a time you mentored a teammate who was struggling with mobile performance debugging. What was the situation, how did you help them get unstuck, and what was the outcome for both the person and the product? If relevant, you can reference tools like Xcode Instruments, Android Studio Profiler, or internal performance dashboards similar to what you might use on a Meta surface like Facebook or Instagram."
This question tests whether you can mentor effectively in a high-pressure engineering environment without simply taking over the problem yourself. For a Mobile Engineer at Meta, performance issues often affect user experience directly, so interviewers want to see whether you can teach debugging habits, prioritize the highest-impact bottlenecks, and raise the overall capability of the team.
They are also looking for influence without authority: can you coach someone through ambiguity, build their confidence, and still protect delivery timelines? Strong candidates show judgment about when to guide, when to pair, and when to step in.
A strong answer uses a specific example with clear stakes, such as scroll jank, startup latency, ANRs, or memory regressions on a real mobile feature. The best responses show a structured mentoring approach, measurable performance improvement, growth in the teammate's independence, and a clear lesson learned about coaching rather than rescuing.