The Artists, albums,tracks buttons are very very slow. At least you should give processing priority for button re-draw so that the user can see that the button has been pressed.
As it is (on an 1.6GB Atom processor, which i use as my dedicated muysic server) nothing seems to happen when I click a button. So I click again, and as nothing happens still, I click on some other button... which eventually leads to SEVERAL buttons showing as selected and several of the sloooooow sorting operations being queued up.
The speed needs to improve, but simply giving ANY visual feedback immediately would be a big help.