o much experience on mac... in cubase check in the prefs so that it doesn't use all the fancy wave redraw and stuff.... can't really think of anything else right now!! (weekend and all :P ).... Also make sure u have only the waves u need loaded... go on the Audio Pool page and clean up.... Check if u r only using a small chunk of a sample but the actuall samples is quite big... if so try and make the edits/ fades permanent... First backup everything .. export project 2 a new folde (file menu), and save a copy of yer *.cpr file there....

Not much I can think of right now.... bad crack maybe!?! ??

Z