McAfee 8.7i and QC 10.... slow
We noticed that after switching to McAfee 8.7i it was taking over a minute to load the client in IE (before logging into a project). The MShield process was consuming 50% of the clients CPU during the launch of QC. After modifying our McAfee policy it now takes < 20 seconds.
Lesson learned is to make sure your virus scanner is not slowing down your clients. Norton did not seem to slow it down, but McAfee really does. I believe it has to do with the level of security the two products implement... and the fact that the new QC client is very large.