I have 1.2 gigs of ram on a p4 and am experiancing large pauses between code changes - mainly when I copy and paste lines of code or the editor gains focus. I have bumped Idea's memory max setting via the .lax to 340 megs.
It's even worse when editing XML files. I have turned off local history but still have the same problem.
lax.nl.java.option.additional=-Xms16m -Xmx352m -Dsun.java2d.noddraw=true -Didea.system.path="~