Good to be back to the grind!
Movement, at present, is probably the dumbest and most wasteful system in the game. For the non-straight-line paths, every enemy's movement direction is recalculated and updated every frame. That's going to have to stop. There's also the issue of all the movement feeling too similar. There's no variance within movement styles, and that could be remedied a number of ways.
Realistically, I'm going to have to fold shared qualities of movement into a class that shares with the whole wave, like I did with Enemy Weapons. Might just clear up some of the FPS stutters that the game's rife with. Because crap, man. Enemy waves are at least half of what makes a shmup a shmup.