R# is really useful, but sometimes, when I’m working to very big web forms or winform projects, and I know that I do not need R# feature because I’m only designing the UI, it can be useful to temporary suspend R#, freeing memory and speeding a little bit VS.
In R#5 the option to disable it is in the Tools->Options menu
Where you can easily stop and resume R# functionality. But the coolest feature is that you can simply disable and reenable R# with command Windows
You also have intellisense :), so you can enable/disable in seconds :)