Hi Jim, it's hard to put any one specific limit on that because a lot can depend on what hardware you're running on.

For example if you're running on a small netbook computer with limited RAM, that's going to have a much significantly smaller maximum workable file size than a quad-core desktop machine with maxed out memory.

So it's pretty situational...

100mb is not necessarily going to cause any problems with MoI, but that is getting on the fairly largish side and somewhere much more than that neighborhood you could need to start doing things like separating things out into multiple files instead of having everything all in one single big file. But it all depends on whether you're seeing things bog down though.

If things are bogging down, one thing you can do to reduce memory consumption is to make the display mesh density to be rougher - to do that go to Options > View > Meshing parameters, and change "Mesh angle" from its default of 10 degrees to something more like 25 degrees, and uncheck "Add detail to inflections".

That will make for a somewhat rougher looking shaded appearance of surfaces but it will also reduce memory consumption by quite a bit on heavy models.

- Michael