SheetMusic visualizer may slow down playback significantly

[NyuBlara]

For example, Debussy's Passepied, which is encoded to play at 170BPM, sounds in practice to play at about 155 to 160.

DOMWorkers to the rescue ?

[NyuBlara]

Actually, I'm starting to think that we're looking at this problem from the wrong angle. Why not put playback in a worker instead — this way, it executes independent of anything happening in the UI thread ?

I've opened issue #111 on the subject.