Fillets seem to dramatically increase an object's size. I have enclosed a simple example of a curved frame without a fillet and one with a small fillet on one 3/4"/19mm wide face, both edges (see pic).

I exported these frames separately as .obj as ngons and at a setting of 9 (if the default setting of the slide at midpoint = 5 and extreme right = 10) so the tessellation would not be perceivable. (Observation: it seems the setting has to be quite high for large curved objects.) The .obj files were then opened in C4D. The file sizes look like this:
Without fillet
.3dm 32 KB
.obj 48 KB
C4D 76 KB

With fillet
.3dm 112 KB
.obj 976 KB
C4D 480 KB

Is there any advice on filleting objects in Moi without causing huge files?

Leonard