I'm having the same issue, and I have a ticket open on it. Post update we're only seeing 35-40% resource consumption but it's acting like full resource use. Prior to the update we were having obvious 100% consumption issues. All the normal stuff like rootkit scanning and self protect are disabled in these groups.
Oddly it only seems to be occurring with the group of machines I have setup to scan with greater frequency. The machines scheduled for a full scan once a week don't seem to be experiencing that issue.
Edit: Never mind someone closed the ticket. I guess I need to reopen it for a 3rd time. I really like the idea of this product but implementation wise I'm spending a lot more time on it than we did with the stand alone products. It's becoming a pretty serious issue.