More object add on the scene,slower the camera rot

[perfectlifepan]

hi~
My project is a first-person game and can sucessfully walk towards and rotate on the scene, but it is not smooth when the camera rotate(many objects on the scene eg 40 trees,hill(128.0X128.0),3 buildings,skybox) with pressing a key.
Can anybody know how to improve that..thank~~

[Breakfast]

How many polygons are in your scene? The number of objects may be less important than the complexity of those objects.

How are you judging how much your camera should move per frame?

[perfectlifepan]

::)I dont know how many polygons are~~

there are following objects in the scene
a 128.0f*128.0f size hill terrain(obj file)30
a gun which attach with the view(obj file),a sky box,some trees(obj file) and ghosts(obj file).

Also, I use a thread to process event instead of KeyNavigatorBehaviour