We have an SSRS Server that has 100's of directories with 10,000's of RDLs spread across them. When you click the Load button, it could take up to 30 minutes to populate the TreeView.
I just got done updating the utility to only load the visible nodes in the tree. When you expand a node, it will populate the child nodes. This makes loading very fast because it is only loading a small subset at a time and only loading the nodes the user actually cares about.
I'm a bit new to github, so will try to do a Pull Request so the changes are available for anybody else in my situation.