When staging files in the split view, the user can move items from top to bottom (staged to unstaged) and vice versa with the checkbox. When performing this action the view is very slow to update. Clearly the technique the software is not WPF optimized. It appears it is rebuilding an entire list/collection, resetting the ItemsSource, and/or regenerating entirely new ItemContainers. The correct way to implement views like this in WPF is to have both ItemsControls bind to the same collection and have the Visiblity toggle from collapsed to visible based on staging.