Any way to speed up transformations on child objects?

When i have lots of gameobjects as children of each other and i try to rotate the root gameobject smoothly, framerate drops from 90-100 to 20-30. This does not happen if there are no children and this does not happen when moving the object only when rotating it. Is there a way to speed it up somehow?

If the children have colliders, they should also have rigidbodies, which are set to kinematic. If you move a collider without a rigidbody the entire physics world has to be recalculated. That might be your problem. Maybe post some detailed Profiler screenshots.