Hi Pilou,

> Export Step works fine but importation (122 kb) inside SimLab Composer Light (free in 1920 * 1080)
> http://www.simlab-soft.com/3d-products/simlab-composer-lite.aspx
> is very slow! (say 4 minutes)

Many operations that process NURBS surfaces are not expecting to work with such a chaotic surface especially with areas that tightly fold back and forth over itself, so you may run into various problems with a surface like that. In general something like that is better suited for a polygon modeling program rather than a CAD program.

- Michael