WPF UI Thread blocked with large collection

Question

I have a WPF application built using MVVM; one of the Views contains a collection of models that can be between 200-500 in length, each of the models are mapped to a Reposit

Answer 1

Look into adding virtualization to your ItemsControl. This way it only renders the items in view rather than all of them.

<ItemsControl VirtualizingStackPanel.IsVirtualizing="True"
              ScrollViewer.CanContentScroll="True">
    <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
            <VirtualizingStackPanel />
        </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
</ItemsControl>

I believe you'd also need to remove the ItemsControl from the StackPanel and ScrollViewer, as they'll give the ItemsControl infinite space to render, and render the virtualization useless.

I see you're using a WrapPanel for your ItemsPanelTemplate, so you may need to roll your own virtualized panel, or check out some other controls (haven't used these myself).