I have noticed that, on all IDEA 8 versions, when I switch away from IDEA to another application, IDEA CPU usage rises to 50% for about 7 seconds. During this period, the IDEA IDE is unresponsive if you switch back to it. This means that switching to another application then immediately switching back to IDEA (for example, after checking a document or browser) always incurs a 7 second delay. This can be incredibly frustrating.
I have added a comment to this effect to the tracker for "100% CPU usage when focus moves back to IDEA" (http://www.jetbrains.net/jira/browse/IDEA-19066), but I'm not sure it is exactly the same problem.
I notice that when I switch to a smaller test project, this doesn't occur.
I'm running a largish project under Windows XP Pro. Does anyone else experience this problem?