I have found that pretty much any time I am running the player with visuals my buttons react very slowly. It is occasionally a little slow without visuals, but with visuals it is for all intensive purposes locked up (though music continues to play). If I have the track timer running, the timer clock only updates every 15 seconds or so. I am running 2.0b11 on a MK1. I am about ready to return to 2.0b7 as that seemed to work much better for me.