I can confirm that there was a SR3.1 for P9/Pro2012.  Among other things, I think it fixed the Internet Explorer 11 problem which a Windows update caused.

     Consider how many polygons the cloth has, and whether there is any intersection of cloth and doll.  Using a lower poly cloth prop and ensuring that there is no intersection of the cloth with the doll may make a dramatic difference.

     How much RAM is enough depends on your usage habits.  I often exceed 8GB.

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