Thanks! You can actually mute the music by pressing m, but it isn't written anywhere in the game so I should find an elegant way of including it. But yeah, after spending a third of my time testing this game listening to it, I don't really like the music either.
What I'll end up doing is breaking the game down into sections with different time limits. The idea behind the bullets is that they would effectively buy you time by letting you easily bypass obstacles, but picking them up could end up costing you time if you don't choose a fast enough route. So the time limit in any given section has to be long enough to make your chosen route matter, but not so long that it feels overly punishing to fail.