Your question is Optimize a Pipeline Bottleneck. 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).
You're discussing a pipeline that started missing expectations as data volume and downstream usage grew. The interviewer wants to understand how you diagnosed the slowest part of the system, what signals you used to confirm the bottleneck, and how you improved it without breaking data correctness.
Describe a time you had to optimize a bottleneck in a data processing pipeline.