game become very slow when going on .3ds object

Hey, I’m creating a game and i need to import 3D model with format 3ds i did it.But i have a problem,my game become very slow every time i get close to this object (it’s stair, and this happen when i walk on it). also the stats tris go from 14k to 800k when i go on it.any one can help me solve this problem!??

You should consider reducing the polycount of your .3ds object by a few hundred percent. 800k polygons are like 750k too much for a stair. Hell even 50k polygons is very much and can only be justified if you have a very very detailed stairs model.