Alternatively, you have parallel_tests ( https://github.com/grosser/parallel_tests ) which can run on multiple cores. That's great if you use a mac pro, or some behemoth machine.
I tried it a few months back, I didn't end up using it. I felt like it was unnecessary, I rather focus on one app than two. I stuck with sabnzbd+ & nzbs.org, after newzbin was taken over.