I recently had a super complex testscene with thousands of objects. Just out of sheer curiosity I opened them up in all 3D packages I have available:
C4D imported the FBX super fast (under a minute) but the scene was unusable. Barely 3FPS, selecting stuff took seconds after the click
3DS Max took over 30 damn minutes to import. Barely 5FPS, selecting stuff took seconds after the click
Houdini imported in seconds, decreased but very, very usable performance. I didn't expect anything else tbh
Blender imported in seconds, decreased but very, very usable performance. The UI snapiness took a hit, but that's about it
After that I can definitely understand why the Maxon team have been reworking the entire software from the core up. It's insane how much faster Blender is in viewport performance, WHILE doing fancy shader stuff at the same time.