Multiple classes inside each other

Hi, I recently started with classes and I have one question. I made class variable, so I can manage it in inspector. I wanted to look it nice so I made few classes inside that class to create some groups for similar variables. It´s working okay, but I´m worried, that those multiple classes will decrease performance. Is that possible?

 var something : First;
 
 function Update()
 {
     //Using variable from second class
     something.position.x_Position += 1;
 }
 
 class First
 {
     class Position
     {
         var x_Position : float;
         var y_Position : float;    
     }    
     class Size
     {
         var x_Size : float;
         var y_Size : float;    
     }
     
     var hasFixedSize : boolean;
     var position : Position;
     var size : Size;
     var header : String;
     var style : int;
 }