Vex, the core i7 is a hyperthreaded quad, and 8 threads will probably be best.  While the main core threads are fetching, the hyperthreads can run so as to get the most total use from your processor.  Galadriel has a core i7 and during a render all four cores hover near 100%, which means I'm getting maximum benefit of the processor's capacity.  The pics below pulled over 10Gb each for a full screen render (2560x1600).

Vestmann, your issue has me puzzled;  let's hope someone who knows more will pick it up.

One P8 flaw which has been fixed is the OBJ import failure for certain meshes.  P8 choked on my Nasmyth catadioptric telescope, great mallorn tree, and spiral stairway.  PP2010 imported all of them.  That's better.   These two freebies will be packaged and released within a few days...

Miri's treehouse closeup, Alyson on the deck...

Elvish observatory flet - Alyson on the main flet level...

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5