I figured it out. The one thing I HATE about Apple, is that they think they know what's best for you, and sometimes make it difficult or impossible to do what you want to do. The fix was simple, but I would have never figured it out without this information from an internet search:
https://www.ihash.eu/2014/12/disable-app-nap-system-wide-os-x-yosemite/
App Nap! Good if you're on battery, but not if you're running a pro audio application!
Terry