Unreal Editor bloat (25000 objs)

If you turn on Editor monitoring to show the fps in unreal it also shows the amount of objects in a scene. For some reason each unreal engine project starts with 25000 (or 2500 i cant recall) objects in a scene. I havent been able to find a reference to this anywhere on the web or in the docs…My question is are these required by unreal for it to run ? and whats the best way to free these objects from the scene if they arent required?..
Obviously these have to have some impact on performance…
I am simply trying to test megascans with unreal and its working but its terribly inefficient even for the size of the scenes. Does anyone know anything about this?