I have a computer which struggles on week 3 and can't even load week 2 or 5 but runs every other level almost completely fine. It's perfectly fine on the final song for week 5, winter horror land , though. (I use a chromebook which was around $100 to $120 USD)
I was also curious if you knew where I could find the mod. The only way I could think of an fps fix would be to cut down on dense coding/files/assets/etc.