Your question is Debugging Production Bottlenecks. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Explain how you would debug a performance bottleneck in a production environment under heavy load. Describe how you would protect users while investigating, narrow the problem using observability data, distinguish between application, database, infrastructure, and dependency causes, and validate a mitigation. Explain how you would communicate status, decide whether to roll back, scale, throttle, or defer changes, and document follow-up actions after service stability is restored.