Major Framerate problem, fulfilled all prereqs before asking for help

Hello all, as of current when I play p64 1.6 Ill have great framerates (around 50-60) then every few seconds they will drop severely to 10-15 fps. This hit happens often enough to make the game unplayable as everything goes into a sort of slow motion for several seconds at a time Every few seconds.
If anyone knows more in depth which settings i should be playing on or which plug-in I should be using or help in general please do not hesitate... I miss the game Mystical Nina Starring Goemon and must beat it again!