Howdy, Jim, et al!
I’m running on a nearly identical setup as well, and I’ve been having serious slowdown issues trying to edit H.264 and .MTS files. Gonna MPEG Streamclip it today, to ProRes (either LT or Proxy) and see how that works.
One other note – I find it’s generally best to have the data files on an external hard drive, of at least 7200rpm. When I put the data files on the same hard drive as the program files, the hard drive has a harder time keeping up – both trying to run the program AND access the data files at the same time.
Hope that helps. 😉