R3 DXF Prob.
This is why I've always thought it's a good idea to save your AutoCAD
DXF file *after* you've exploded all the blocks in the drawing. It
gives some idea of the complexity of the drawing.
Far too often, a drawing passes from engineer to engineer, from client
to 3D artist, and no one has a clear idea of what's in the file, in
terms of blocks, entities, etc. If you tell the client to explode
everything, and it turns into a 30 meg DXF, then they'll have some
notion of how difficult it will be to animate.