Number of tris in scene grows with scale of mesh?

I have a scene with about 5k tris total(with one light and soft shadows). When i add one plane(2 tris, unlit texture material) to scene triangle count rises to 5.1k. OK(not really). But when i set scale of plane to 200 x 100 x 1 the triangle count grows up to stunning 10k. How does scale affect tris in scene so radically?