Poor performance on large visual

In my scene the framerate drops dramatically when I set the camera to see the whole scene.
is there a way to decrease the detail of the models displayed when viewed from afar?
thanks

Pro users have access to Level of Detail. See:

Either create a LoD script which does a lot of math of calculating your distance from the object, and then a switch statement of which level of detail the engine needs to load. Or, save up and purchase Unity Pro which has it already included.

decreasing the detail of the models did not change anything.
I solved by grouping all the static objects in a single object and attacking the script “combine children” located in “standard assets”