Quote -
If you want faster renders, go to Edit > General Preferences, click on the Render tab, set the "threads" slider to 4, and click the checkbox underneath. This will allow the FireFly renderer to use multiple processors (if you have them) and separate memory threads.

 

AHA!   I set the slider to 4, but I didn't click the "separate process" checkbox...  Makes sense.  Gonna try it.  Thank you!