I got to the part where you climb upwards through multiple screens and there are 4 coins at the top. When I colleted the 4 coins (I think the 2nd or 3rd coin I touched) it did a transition and then just stayed at a black screen.
Yes, I did not know how to transition back to the main screen and the code was a mess so I kind of left it as is :P
EDIT: Ending is now fixed and lag is reduced.