I described a project during my internships where I had to optimize a large data processing script that was taking hours to run due to inefficient algorithms. I implemented a more efficient sorting algorithm and utilized parallel processing, which brought the runtime down from 5 hours to just 30 minutes.

The interviewer seemed impressed with the specific metrics I provided but asked about any challenges faced during implementation. I revealed that I had underestimated the complexity of debugging the parallel processing issues, which led to some delays.

Although I felt I handled the challenge well, I sensed the interviewer was looking for more insight into how I managed stress during that time, something I didn't elaborate on, and I could tell that may have been a missed opportunity.