Kitbash 3D models - Slow? How to Speed up?

Hello everyone-

I purchased some Kitbash3D models. Upon importing them into Blender they are extremely slow to load.

Any ideas how I can speed up the process? I’m running 64 gigs of RAM and an i7 8700K CPU with a 1070ti GPU.

Thanks!

Are they in blender format or 3d, obj, fbx or …? (How much million vertex?)
Then maybe export them in a blender file as library and link…?