I'm making a model of human anatomy . there is about 2100 mesh and model.
I used Helix 3d toolkit to import all files into a scene but that takes a long time to import (about 20 second) and scroll and rotations are slow. and that takes 800 meg of RAM.

objects are optimized and the sum of vertics must be less that 2 million. 

i don't need shadows or any special effect. but i need scroll , zoom , hit testing and ..

what format should i use for saving models? i think .obj files are slow. should i use 3ds? or xaml?

should i use 2000 modelvisual3d or one with 2000 Geometrymodel3d ?

or should i use XNA?

can i disable some features to speed things up ?

tnx