UI Freezes (takes long to load) with sufficiently large list of items in a combo box. Introduced in PR #1645

Describe the bug

UI Freezes (takes long to load) with sufficiently large list of items in a combo box. Introduced in PR #1645

If I remove the wpf style from the combo box and set the ItemTemplate to VirtualizingStackPanel it loads almost instantly.

This is also a memory issue, as if I have a list of 20k strings I am throwing in this ComboBox it creates 20k items in the visual tree.

The red arrow below is before I click the ComboBox:

The app runs at 300 mb -> I click and it balloons to 1.4 gb.

To Reproduce

Create a list of strings that is sufficient in size, bind it to the ItemsSource and then run, expand the UI and you will see everything I described.

Expected behavior

Run the same code in PR #1703 (changed StackPanel in the ItemTemplate to VirtualizingStackPanel) and you will see the issue is resolved.

Screenshots

OS version

Windows 11

.NET version

10

WPF-UI NuGet version

4.2.0

Additional context

Fixed in #1703

Start by comparing the combo box changes in PR #1645 and the reported fix in #1703. Reproduce the issue with a large string list on Windows 11 and .NET 10, then verify that expanding the combo box avoids creating all 20k visual elements and no longer causes the reported loading delay or memory spike.