I love this game, but I never came past the third level, and only once past the second.
The mouse seems to behave a bit wired, I guess it is because of the framerate, which is around 25 to 35, that's way to low for a casual game on my pc, although my pc is by far not new. I don't whether it helps, but when clicking F11 twice I see that the flat terrain has a bunch of tris that are not necessary at all.
I hope that you are going to make a lot optimzing as well, because I like to play that game, and I wish you much success with sales!