I have found in my experience with Bryce that other model formats load much faster than .dxf. I have had big .dxf files take ten minutes or more to load. Sometimes they take so much time that it does seem like the program is frozen, but they load...most of the time. Lots of free progs out there to convert a .dxf to a more easily digested file like a .3ds or .obj file. Check out the Modeling Forum too. Maybe some of the other folks in the Forum can recommend some.