Just putting this up as a reference the next time this comes up on HN. The study data shows that the median task is 1.5hrs and the 15 minutes that developers think they saved was actually more than that many minutes less researching, testing, and writing code and the 15 minutes longer they actually spent was more idle (5mins) and waiting for AI (5 mins) and reviewing and prompting dominating their work over actually writing code.
The person who showed a speed-up indicated over a week of prior experience with cursor while all others under a week.