Custom FixedTime?

Is there a way to create an Alternate Fixed time update?
I’m currently using the unity FixedUpdate for player movement which I need to run at 60fps for consistency in motion. The problem is the Physics Engine uses the same interval to update and uses unnecessary processing. My game runs on iOS so it is important for efficiency.

Is there a way to create a different fixed update thread using Invoke or something?

You could use a coroutine, maybe: http://unity3d.com/support/documentation/ScriptReference/index.Coroutines_26_Yield