You might want to add a non-HD setting, I have a low-end PC and even on 720 the game bugged so much I couldn't even finish #1.
What sort of issues were you experiencing? Lag or crashes?
MASSIVE Lags. And a framerate of maybe 6 or 7 FPS.
Hmm sorry to hear that. I guess it's cas the game is a little bit demanding, in terms of having a bunch of levels active at the same time. I didn't have enough time at the end to optimise the whole thing unfortunately :/