Ah I don't have this emulator but look at the Game Settings and look for Frame skipping and see if you are able to lower that to 0 or to a point that it runs at the correct speed
Also check Settings in the gui that shows on boot and see if anything to do with the system has been changed to alter FPS or clock speeds to something higher than it should be
Maybe I should check this emu out now myself, I did not really bother as I own a PSP anyway but this has some nice features now compared to what it did have
Retroarch is also worth looking at that includes a PSP core as well as a ton of other systems
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