Speed of rendering??

I have a engine which loads 3ds files makes compiled lists and then puts them on screen. The porgram works but fine. it managed to keep a very good frame rate with a 5000 polygon object, with a single texture, but it dropped when it rendered a 200 polygon object with 2 textures. none of the objects have blending, bump-mapping or anything else, just a plain bmp. What is wrong??