Scrolling in virtualized WPF TreeView is very unstable

Question

If virtualizing is enabled in TreeView with items having various sizes, multiple problems appear:

• Vertical scroll bar changes its size randomly and

Answer 1

By default Virtualization Stack panel uses pixel rendering to render child elements and the Recycling mode will discard each elements inside the treeview container that is no longer needed in UI. This cause the scroll bar size to change automatically. The VirtualizationPanel Pixel rendering technique will leads to slow down the scrolling option also. By changing to VirtualizingPanel.ScrollUnit="Item" will solve your issues. Below xaml is working fine for me