I noticed that the default theme of ubuntu studio 10.10 is very slow on a Toshiba Portégé R500 laptop (GMA945 video, no desktop effects, 64 bit install). I noticed this while watching the updater app while moving the popup window with the progress info. For some reason it is very strong for this one application. Instead of lossing too many words, I will attach two screenshots. Both are taken short after moving the popup window, causing redraw of the window now being exposed. The default theme shows serious lag there, while the Clearlooks theme is not that slow (you don't see anything out of the ordinary on that screenshot).
Anyhow, I think I should mention this ... as such redraw "performance" makes the desktop feel way more sluggish than ... well, I'll stop before I write down some insulting comparison. Since the choice of theme affects this, there might be something to do to fix that behaviour. Though I am puzzled: How can you make something like simple white text on black ... slow? Especially compared to the other themes?
Default theme has changed several times, and Ubuntu version in question is no longer supported. Closing.