I think Carrara files that are imported from Poser are absolutely larger than the original Poser file. How come? Tolerances. I think that C5 translates the data to very tight tolerances so that the end result is as true as possible to the original Poser scene. That being said, C5 STILL renders them far faster than Poser. And WILL render scenes that Poser won't even attempt. I just did one like that today. Gorgeous results in C5. Poser puked before even doing ANYTHING on the same scene. Memory error.

And yes, it's the high res textures that do it. Use a lot of them and Poser just dies.