I'm happy to rebuild the binary when I'm stuck on a performance problem. Obviously, the best case is having all the instrumentation on the production system that is experiencing problems, of course. I've run into problems that only manifest themselves after running for several hours, so the debugging cycle is slow when you aren't collecting what you need to debug the issue. In other cases, I've had bugs where a test case can reproduce them immediately, but the profiler still provides more targeted guesses than randomly changing something to see if it improves the outcome (even if the edit/test cycle is fast enough to support this). That's the case where this sounds helpful.