Newbie question. Turning on Bucket rendering

I just noticed something. I started a Vray rendering from an old file and it just renders by coming into focus, kind of like Maxwell. The progress window says it is just rendering to one thread.
Looked thru the settings and don’t see where to set the threads used. Is there such a setting? Thanks.

S. Houtzager

Light cache options → number of passes: set it to 0 and Vray will use all cores.