I know, it's an old subject, but it kind of doesn't go away.
I've just installed VS 2012 and R# 7.
Before installed R#, VS took 1-2 seconds until it was responsive, and another 3 seconds for the (big) solution to open and show a previously opened file .
Now, with R# installed, it takes 6-8 seconds until VS offers the Start Page with the list of recent projects. About half that time is actually spent with an empty workspace in VS until the R# menu item appears and the Start Page shows up. Loading the solution with R# also takes about 8-10 seconds.
I figured, I'd post here first before starting a feature request.