3ds Max displays a warning when you import very large-scale geometry.
AutoCAD allows you to create geometry that is very far from the origin or contains a very large bounding box. When you import such a drawing into 3ds Max, because of roundoff issues, viewports and transform tools do not respond properly and the cursor does not move smoothly.
For example, if you have a file that is a mile wide, but your system units are millimeters, you have a scene width of 1.6 million units, which is too great a value. If you change your system unit to feet, this is less taxing on the system.
If any side of the scene's bounding box measures larger than ± 1,000,000 system units, you will see the following dialog:
When you see this message, use the Rescale checkbox on the Geometry panel to choose a unit that is easier to manage in 3ds Max.