Quote - monkeycloud, your numbers don't sound to me like your system is running out of memory. There might be other things preventing all threads from running simultaneously. Did you by any chance turn off texture filtering? Should we take this to a separate thread maybe?

Hi Stewer

I do have texture filtering set to "none" on some Image map nodes... set to "quality" on others. What are the implications of that?

I think I should probably install SP2.1 in the first instance and then, assuming the issue is still there, I will start a new thread for this...

...I can then follow aRtBee's lead and do some more diagnostics. I'll see if I can chart the process life cycle under OS X somehow.

I'm running a QM render now using BB's suggested option #1 above... I left it running overnight, but having come back to it, it seemed to have reached just over 66% (end of SSS pass?) and was sitting down around 150% CPU. Memory usage about 5 GB real and the same in virtual / swap.

So have left that running for the day...

Anyway... a new thread on this in due course I expect... I can run through a table of render settings, based on BB's suggested heuristic values, more systematically, and take some actual measurements...

Cheers ;-)