Drag finger around screen to see the choppyness. If it isn't choppy press kill and try again. When it is choppy press the play/stop button to see how starting the sequencer somehow fixes it.
dave234/AudioTouchConflict
A demonstration of The MusicPlayer Framework causing a UIPanGestureRecognizer to miss frames when a GLKView is being refreshed by a CADisplayLink
Objective-CMIT