Only way seems to be optimizing/cleaning/collapsing 3d models before bringing them into unity, but that loses information, parts are not individually select-able and other limitations.
Are there any other options at the moment? (its mostly the unique & visible object count that kills performance, examples: +200k objects, +100m vertices)
#what is currently the best way to display large full CAD models in unity (desktop applications) ?
sleek sandal
hidden anchor
You could look at Pixyz, which is a product specifically made to optimize and import heavy CAD models : https://unity.com/products/pixyz
But generally, no, you can't directly import CAD models without a minimum of processing to use them in real time applications.