Quote - "Is this automatic in Bryce 6? or does it need some User intervention?" Within Bryce 6.1 the CPU priority can be set to 1, 1/2 or all of the cores. This does not result in 4X render speed but it's a huge render speed increase over a single or dual core system.

WHAT???!!! You mean Byce 6.1 can actually use the entire CPU on my venerable hyperthreaded P4 3.2GHz machine?? What a revelation! I always wondered why it only seemed to use 50% of the CPU and no matter what I did in Task Manager, it never helped at all! The solution was right under my nose! (For those who don't know, its under Render Options, Priority - can't believe I never saw it before!) A big Thank You to Dan Whiteside for pointing that out, but you really should've told me before I did a render that took over 25 days!! :-)

Its like having a new computer!