Also try adjusting your Image Quality settings this will affect your performance. FYI the more sheets you get the slower things will be. SW hasn't quite gotten the multiple sheet drawing thing down yet. =(
Corey
(BTW I have a model of a casting, nothing too special like an engine or anything, relatively simple but It is on 3 sheets with a bunch of section cuts and man it got bogged down. Though recently I did a small assembly with just tubing and sheetmetal and had 5 sheets no sections and it didn't seem to do too bad.)