Afaik JPCSP is a high level emulator. It doesnt really emulate the PSPs hardware, which in case means there is no CPU you could overclock. The emulator always runs with max. speed as long as it runs at anything below 60fps.
So if your game doesnt run at full speed this just means that it uses functions that are either not yet implemented in JPCSP or just not optimized.
So if your game doesnt run at full speed this just means that it uses functions that are either not yet implemented in JPCSP or just not optimized.