Treeview slowness

I have a treeview with an unusual structure that is populating extremely slowly. It has only one root node, and then a branching factor for the first level that ranges from 1 to as high as 10,000. The second level has an average branching factor of only 1.3 or so and is entirely leaf nodes. Naturally, this makes populating the tree view extraordinarily slow. Does anyone out there know of a commercial package with caching tree views that might be able to deal with this kind of problem? I tried looking at the threaded treeview in the codeguru libraries, but that seems more appropriate for deep trees with a smaller maximum branching factor.