i tried running muse 0.8, 1.1 and 2.0alpha on my debian lenny system (with xfce, mainly a GTK-based system, but also qt3 and qt4). It seems to work quite well (didn't test it fully), but it's causing xorg to produce an extremly high cpu load;
this happens when i move the mouse around in the window, where the "miniatures" of my tracks are displayed (cakewalk calls it "clips") (the thingy on the right side); it also happens, when i have the window big and let it play; HOWEVER, it doesn't happen, when the window is so small that the "miniature"-part is not or only at a small part visible.
with muse 1.1, i also noticed, that when hovering over the buttons, they seem to lag. i move the mouse from left to right, and after a second or so, the buttons respond to this (i.e., they are "lit" a bit, as my qt theme tells them to)
this does not happen with other qt applications (well, maybe with one or two), so i think this is not an xorg or qt problem, but mainly a MUSE problem
i've also run it through xscope, that produced a 52MB log, however, which i only attach if you explicitly want that;
i have, however, attached a summary of this log, showing which kind of request is done how often; i hope that helps