AdvancedDataGrid performance with...

I have an AdvancedDataGrid and I'm loading a few thousand rows of data.

The data I have is hierarchical and I am lazy loading the tree. So if a data item has children, I add a child that says ''Loading...''.

Then when that data item is opened (expanded) I remove that child then make another call to load the children for that item.

That part works fine, there's a slight delay when opening a branch, but that's to be expected. However, when I close a the branch, there is also a delay.

Any ideas why there would be a delay when closing?

Thanks.