I see! I assume the sort of CAD should be the same, so the same advice applies - i.e., reduce the resolution to reduce the number of faces or alternatively and preferrably go for a non-faceted model.
As a last resort you can try and import the file as STL (also with a lower resolutions) to see if the automatic facet splitting works in merging your CAD’s faces. Keep in mind you’d probably get good simulation results in this case by using the CHT IBM solver I’d mentioned.