I'm glad you found the game to be cool!
And for flight ability, you have to release the spacebar to actually initiate it lol that might be why you felt it was slow.
For Frost....Yes that's a game breaking bug that I wasn't able to fix (Frost ball one shots speed if you shoot it right next to him but it is fine if you shoot it from a distance). Speed's Phase 2 has the most interesting attack patterns...and it's like that level is the whole reason to even play this game (if only the bug wasn't there).
Anyways Thanks a lot for playing!