Easy as it could be: full 60 FPS - without vSync even up to 700 (?!) - but extreme lags if 3 or more enemies appear. Funnily the FPS don't even drop that much, maybe 40-50 FPS, but still the game feels like maybe 5 or so.
CPU: Intel i5 (Quad)
vSync on / off - no change.
all four cores / only one core - no change either.
Help, pls? Afaik this didn't happen on either retail nor Steam version (yes, I bought the game as often as I could^^)