A coworker of mine was having some pretty significant performance issues with navigating in CRM 2011 on his machine prior to a client demo the other day. After telling him it was fine for me I went over to his desk and saw the issues he was having. I tried disabling all of his add-ins and asked him if he had any virus software that might be causing the issue or if he had issues on other sites that could point to a general performance issue on his machine.
None of these things seemed to point to a problem until, by chance, one of the CRM windows opened and the performance issues were gone. The only thing I saw that had changed was the zoom setting in IE had gone from 90% to 100%.
It didn’t seem likely that was the problem, but I set it back to 90% anyway and voila, performance issues were back. I then went to my computer and performed the same test and got the same results.
At 90%, CRM was pretty much unresponsive. Switching to 100% fixed it. I found this article which does mention the zoom as a factor in performance as well as some other client related performance tricks.