Do I have to add rigidBody even when the movement doesn't use physics?

Questions & Answers
1

I heard that adding RigidBody component to a moving object saves some kind of RAM capacity or something. But does it have the effect even when the object’s movement is not physical?

What I mean by un-physical movement is for example,
instead of using AddForce, use gameObject.transform.position + new Vector3 (1,0,0)

2

If the object has a collider (or colliders) AND it moves, then it must have a Rigidbody. If the object is only to be moved by altering its position and not via AddForce or physics collisions, set rigidbody.isKinematic to true (this is called a Kinematic Rigidbody).

If the object has a collider and will never, ever move, it does not need a rigidbody, though you can add one (this is called a Static Rigidbody).

If the object has no colliders it does not need a rigidbody and you generally shouldn’t add one.