What is the performancedifference between classes and object instances?

Hey,
I talk about the the performance cost of one created class that use 100 object instances in game or 100 classes with the same code that is used as object instance once in game. So we have in both scenarios 100 object instances. Let´s say that contain the simple ai movement and some abilities like dashing forward, changing some values, or toggling the movement. How much more does the second scenario cost for loading the Level and playing the Level?