Question Delay when doing DragAndDrop from script

I have a script that allows me to drag and drop objects in the hierarchy type view. It is working and I can drag and drop to change the tree but there is an anooying delay. Unlike the Unity hierarchy view where when you move over another object you can drop instantly with my version I have to wait until the item registers the mouse is over it before I can successfully drop the item. I did a little gif showing the delay. Does anyone know what could be causing this.