Hi Pilou,

try Instant Meshes! (https://igl.ethz.ch/projects/instant-meshes/)

I exported an obj of around 8K polygons, pure quad mesh with a file size of 3.5MB. Imported nicely into Moi3D.

3dm file was around 88MB but it looks clean and i can boolean diff a sphere in 10-15 sec on my MBP :-)

Playing with different polygon counts is easy in Instant Meshes so give it a go!

Dinos