ActionScript 3.0 :: Receiving Untyped In Constructor Will Slow Class Down?

I'm almost certain that creating and accessing untyped data causes some performance penalty vs typing data properly. I am creating a class that accepts an untyped data in the constructor, and assigns that data to a local class variable as such (pseudo code):

class myClass{
private var foo:*;
function myClass(inData:*){

[Code].....

To my understanding, im just passing the 'reference' of the stage or some display container into myClass right?

Even if there is a performance hit, it would upon class instantiation when myClass is created where the untyped foo is created. So, in thats the case, using untyped data for foo won't effect performance? Since there is no direct accessing of foo?

Or is there 'access' on foo in the update function since update() resides in MyClass and so does foo. It wouldn't matter much if its just a normal class but my whole application's update works in this class so if there is any performance issues, it's gonna effect everything else.