Speed up TreeView Control?

I'm working in a TreeView Control for a GUI, I'm using GUIDE and the control is an Activex, I have no problem generating the nodes and the tree itself, but the performance when it comes to process several nodes (I'm trying to display a tree with more than 1000 children) the time it takes the program to finish is a lot, almost 2 hours, I read that when it comes to this problem the functions BeginUpdate and EndUpdate comes very handy and solve this problem, however, I can't find this functions anywhere; I believe they're not implemented in the Activex control, my questions is: are this functions not implement in Matlab GUIDE? and is any way to speed up (beside the mentioned one) the TreeView control performance? The nature of a TreeView control is that every time a node is added it re-paints the whole tree, so, when comes to a lot of nodes is very inefficient.

Thanks!