Hi Igor,

> Will such spliting affect performance of a MoI model? when it
> will be preferrable not to have it switched on?

Well, the main thing is it alters topology - things like edges that cross the split line will be split into 2 edges rather than staying as one long edge.

It can be nice to keep edges longer when possible, it makes some kinds of operations that work by selecting edges such as fillets to be handled easier since there are less pieces to pick.

I don't think that you will have much choice but to leave it enabled for going into Revit though, since Revit just does not seem to handle closed surfaces.

- Michael