Install Main Runtime on DBMS

Hello, 


I'm working on a new install of V12, and I remember from Sage Sessions several people telling me that the new Best Practice is to put a processing runtime on the DBMS server.  That it would speed up batch processes exponentially. Can anyone confirm this?  If so, should it be the main runtime?  Seems like a lot for one VM, but I've been mistaken often before.  

Also, does anyone have any good migration steps for upgrading V11 to V12 by copying the folder from the V11 environment to a separate V12 environment?