triss count to high

I have problem with triss. I downloaded 3D model of terrain which had around 4000 triss. When I ran the game in the included scene, triss count in stats was around 4,1 k. When I added the same model again triss count doubled. Nothing unusual, but when I put that model to my scene, where was only one cube, my triss count was above 150k. The same case happend again with another model. In the included scene triss number was around 170k, but in my scene 400k+. How can I fix this problem?