How to Avoid Unity Adding Vertices to Object?

I’m importing a .obj with 402,245 vertices into Unity. Once in Unity I’ve found that the object has 585,235 vertices. To confirm I used the Linq library to find that the vertex array contained 182,990 duplicates.

That’s a lot of duplicates. Why is Unity adding all of these duplicates? How can I get rid of them? It’s putting a serious strain on my program’s performance.

If anyone still wants to know, I believe that it happens because Unity imports the object UV map and adds duplicate vertices along the seams of the UV while building the mesh. My shape is pretty complicated, so the UV is made up of many small pieces and seams, which results in the large number of duplicates.