What effect do the priority settings in the conf file have?

I've tried different combinations in an attempt to figure it out but can't see any difference.

Maybe it's staring me straight in the face but I still don't get it 😊

# priority -- Priority levels for dosbox: lowest,lower,normal,higher,highest,pause (when not focussed).
# Second entry behind the comma is for when dosbox is not focused/minimized.