Whats on,

If u mean rendering your samples to audio then yeh thats the best thing to do. As long as you keep the vst instrument there you can come back to it if it needs editing. Just turn it off. Also try not to have too many double delays or reverbs running as they use a surprising amount of your cpu usage, just stick em in you sends.
I had problems like this when using cubase, but that usually stops them.

cheers