moving bullets really isn't a problem, as long as you don't have too many...
In my program bullets will move 3000 units a second on full speed at a constant 30 FPS... when you have more than like 15 bullets active, it does indeed become a problem and the game will slow right down to about 4 - 5 FPS...
You shouldn't need to keep your bullets for more than about 5 frames, if they've not hit something by then, it's probably too far to see the object you hit anyway, so delete it...
if you have loads of other objects loaded, it might be an idea to move it 5 times in the same frame and delete it again, so you're only ever dealing with 1 at a time, and keep the FPS high-ish...
...maybe one day I'll finish a project
