Virtualization in WPF is amazing when you get it, annoying when you lose it. I’m working on a form where the user can dynamically filter and sort a ListBox. I’m using a DataTemplate to give a nice card-like view to each object, which makes it take up a lot of space on the screen. To fix this I used the WrapPanel as the ListBox’s ItemsPanel.
WrapPanel is not virtualized, I can’t find one that is and don’t have any time to write one myself. So I came up with a work around to give the user a fixed number of column view using the standard panel for a ListBox. This got me virtualization back. Then I wanted to smoothly scroll so I turned ScrollViewer.CanContentScroll to false. Smooth scrolling, no virtualization. Because this box may have thousands of records in it, performance is much more important than smooth scrolling.
The moral of the story is, if you’re working on something in WPF and performance is important and you might have a large dataset coming in. Double check your changes to controls to make sure you’re maintaining virtualization. If anybody has a good list of what disables virtualization (grouping, custom panels, smooth scrolling), I’d like to see it.