Well... okay, it has hit the final Render pass now.

CPU dropped back down to between 195 to 205%, Real memory at 5.57 GB and Virtual memory at 5.96 GB... but admittedly my total used RAM is now sitting at 15.15 GB... so only 850 odd MB free RAM.

So I guess it is probably CPU to RAM ratio that's causing the CPU usage to back off???

I guess I'll see what happens when I revert to rendering the same amount of scene content, but without any lights per se... just IDL emitters.

;-)