Your question is Owning a Critical Performance 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).
Tell me about a time you found and resolved a serious performance bottleneck in a software system you owned. Walk me through how you diagnosed it, how you decided what to fix first, and what impact your changes had.