I believe that there are some Mac specific multi-core issues being addressed along with a cross platform memory leak in the next release according to the bug tracker. I personally have been avoiding the Transposer thing since I can do everything from within Carrara. That DOES make a huge difference in how Carrara manages resources. While I like the Poser walk generator, once you understand the Carrara non-linear editor, you can get similar results just as quickly.