Dear illidanx,
Could you, please, clarify one question. When I am running Pokemon (2 generation - gold silver crystal) - turbo mode works fine (set frame skip param to 4 the result fps is about 45), but when I am trying to enable the same turbo mode on Pokemon (3 generation fire red leaf green or emerald) - fpps falls down to 10-15 value. Is it caused by hardware? I tried on bouth vba8 and vba10 on my Lumia 830 and got the same result.
The nature of turbo mode is that the app will emulate more instructions per frames, which needs more power. When the cpu reaches its limit and the app try to emulate more per frame, the frame rate drop downs. In 2nd generation pokemon games, the cpu requirement is lower, so the cpu does not reach its limit.