I've been using ReSharper for a few years, but with R# 7, the performance has gotten so poor that I have to keep it disabled 90% of the time and only enable it when I need to use one of it's features. It causes Visual Studio to hang constantly in all but the most trivial of solutions. Other VS extensions solve this issue by using their own processes to do work. For example, I also use Visual SVN, which uses its own process, and I've never once had VS hang up while waiting for it to do something.
Are there any plans to put R# in its own process? If not, I strongly suggest it is something that should be considered. Having an unresponsive UI in VS because of R# being a performance pig really decreases productivity, exactly the opposite of what R# is supposed to be for.