Most efficient/fastest way to rotate object around another object

What is the most efficient/fastest way to rotate many objects around another object in a circle, like planets and sun ? All action is in 2D, it will be a game for android, so i would like to know, if i'm not doing anything very inefficient. I will have, lets say, 1 "sun" and 100-1000 "planets". Right now i have empty GameObject - "sun", it has many childs - "planets", and "sun" object has its own little script, and in that scripts update method i do "gameObject.transform.RotateAround (point, axis, angle);". Is there more efficient way to rotate many objects around another object ?