I have more detailed stuff via a 50MB Alibre Stp

Which converts to a 75MB MOI stp (about 10 mins)
and a 132MB 3dm file (a few minutes)

It's the processing time for these things when you're just experimenting, it starts to get silly pretty quickly

If you're getting money for a job no doubt it's worth more hassle

edit: I've converted the lumpy 20MB to fbx and it's processing back into MOI
So far I've done the washing up and 5% is done. Going to walk the dog now.
MOI is using 14GB of memory in task manager atm