I seem to have similar problems. I get crashes mid-battle as well. Mostly due to my fully custom models if i'm not wrong, which I believe is a bit too high in vertex/poly/triangle count. Although it is only 1804 vertices and 2406 triangles (the first screenshot), and 2094 vertices and 3278 triangles in total (the second screenshot).
What is the optimal vertex/poly/triangle count for a unit model? Please don't tell me to check a vanilla model and compare, I want somebody's personal experience.
Sometimes the models ingame work perfect, texture, animations, everything. But the weapon (which is custom also) uses the texture of the Figure instead of Attachments, despite me already assigning the weapon in MS3D to Mat:Attachments, and specifying where the texture is located in BMDB. Any help?
Two examples:
The weapon in the second picture is about 800 triangles. Great lag/freezing with only 3 of the same unit, let alone a full army of them.