Citra: An Experimental 3DS Emulator

I'd really like to read about their experience with the emulators performance, profiling and how the work with that aspect.

I remember an old emulator for the DS (can't remember the name though!) that got a massive speedup going from 0.9 to 0.9.1 (the numbers might be wrong, but it was a "minor update"). The guy developing it had found some innocent looking code near the critical loop that was actually crawling like a snail and replaced it with some other innocent looking code that worked a lot faster.