Casting to Interface vs Actor

i know ur first point, i am asking about the second point.
imagine i want to get a bool from my character object so in utube they create an interface that returns that bool and cast to that interface instead of casting to the who character object as they r saying that is faster and save memory. but in OOB interface is not used for this approach i think, so i want to know before i cast to my character in many class if casting to interface better.