Unfortunately, Carrara is still only a 32-bit application. It can theoretically only use 2 GB of RAM. In practice, it will use less than that. Until Carrara becomes a 64-bit program, I'll be spending no more money on "upgrades" (I'm still with 6.2.1). The more advanced features that are added, the more unstable Carrara becomes in its 32-bit form.
Daz obviously could care less about advancing Carrara into the 64-bit world. They seem to only consider it a vehicle for their (mostly mediocre) content.