Adding a class with Generic Lists inside a Generic List

So I have t$$anonymous$$s class for character dialogs and I'm building a set of Lists using it

 class ScriptStep {
     var stepType : StepType;
     var subScript : List.<ScriptStep>;
     var stepDuration : float;    
     var stepTransform : Transform;
     var audioClip : AudioClip;
     var textLine : String;
     var stepAction : function():void;
     var stepActionFade : function(float):void;
     var stepSelectedObject : Obj_Properties_Class;
     var stepPlayerTask : PlayerTaskList;
     var stepWifeTask : WifeTaskList;
     var stepBurglar01Task : Burglar01TaskList;
     var cooperateScript : List.<ScriptStep>;
     var refuseScript : List.<ScriptStep>;
 }

Everyt$$anonymous$$ng is working well until I realized that by adding those 2 extra variables in the class:

         var cooperateScript : List.<ScriptStep>;
         var refuseScript : List.<ScriptStep>;

My .unity file size changes from 600k to 100Mb and the game takes ages to run when I press "Play". Everyt$$anonymous$$ng runs fine but its like I added a huge slowdown.

If I remove those 2 variables in the class everyt$$anonymous$$ng goes back to normal. I would like to understand why t$$anonymous$$s is happening. Am I typing the variables badly? Am I not allow to add a list inside another list?

Any help very appreciated!