even though ZK-1698 was fixed the tree performance with MVVM is still alot worse than MVC especially with bigger trees
sometimes MVC when opening nodes in the attached example both the MVC and MVC-template are about 10x as fast as the MVVM implementation.

this is especially bad, as the tree is in paging mold, and even if only 10 nodes are sent to the client, still all 1000 sub-nodes are rendered on the serverside (this happens in both MVC and MVVM, only that MVVM requires much more time to do the job)