The problem is you have modeled clean, degree=3 NURBS curves. AutoCAD DXF/DWG does not support NURBS curves so they have to be converted to something else. That usually requires converting the NURBS curves to chains of arcs before exporting and that’s a hassle.
IGES support this smarter NURBS curves and if your CAM application supports IGES, the conversion to G-Code arcs and lines is automatic and tweaked for the machine you’re using so you don’t have to think about it.
DXF should be considered a tool of last resort for Rhino curves intended for CAM.