How can I get a horizontal virtualizing ListBox?

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WPF

ListBox

From MSDN, I found that ListBox uses a VirtualizingStackPanel as the default ItemsPanelTemplate. The default stackpanel is vertical, in my project I need a horizontal one. So, I set the ItemsPanel property:

<ListBox.ItemsPanel>
    <ItemsPanelTemplate>
        <StackPanel Orientation="Horizontal"/>
    </ItemsPanelTemplate>
</ListBox.ItemsPanel>

Yes, it works, but I find the virtualizing feature is disabled. When I bind 10000 items to the ListBox, the UI take 5 seconds to load data. Obviously, it's terrible.

I don't know why. Can someone help? I appreciate very much.