Mapping =/= Modeling
Oh really?
... Make an object in blender/sketchup/whatever, export as DTS, open torque constructor, import static mesh, position it, export as dif, put in game, bam.
Thats the way I made maps and stuff... but I think I get your point.
Anyways, ontopic:
I have once experienced lag from interiors. I don't think they're quite different.