treeview - c# How to dynamically add tree nodes during runtime -

I try to dynamically add nodes during run-time to emulate Windows Explorer in an existing treeview I am doing I have a code that works, but because of the amount of repetition it takes 2-3 minutes to check all files on the c: drive and make the tree.

What I want instead is something like this:

  -NodeClickEvents- if there are children {nothing} other (add children and grandchildren to the selected node)   
 This is because it does not have to load the entire tree, instead it loads some layers on a per-click basis.   
 
 
  
 Look at Demo 2 in the same article  
 When creating a TreeView item, attach a dummy object, at the expansion of each tree view item, remove the dummy  
 This is clearly described in the quoted text of