Few thinks you should have in mind when binding RadTreeList:
- RadTreeList need to iterate through all it's data source in order to group the data to be displayed
- RadTreeList binding performance depends on the structure of the data source, i.e nested levels, which items are expanded etc.
- RadTreeList performance depends on whether paging is enabled or not.
I've tried on my end binding to 17 000 records flat structure/only root items/ and took less then 3 min to bind and render RadTreeList.
However along with the new futures for RadTreeList we are working some optimizations in RadTreeList mechanics.
All the best,
the Telerik team