3D is definitely one of the most intensive processing tasks and always takes time, especially when you increase the output resolution. It also depends how large texture maps are and how optimised the object geometry is. All takes up a lot of ram though when processing and the more the better.

In fact, even back in 2000 the design company I was working for at the time had a SGi workstation with 4GB of ram specifically designed for 3DSMAX. But one mad thing about that workstation was that they only included an 8GB HD! Mad.