Windows Phone Scrolling Chat Viewer

I have a combined silverlight xna project in which I am rendering a tile based background. Over that, I want to be able to render a scrollable chat window. I tried adding the following:

    <ScrollViewer Grid.Row="1" Height="48开发者_如何学运维0" HorizontalAlignment="Left" 
                  Name="scrollViewer1" VerticalAlignment="Top" Width="263" 
                  BorderBrush="Black" Background="#8CFFFFFF" FontFamily="Comic Sans MS" 
                  Foreground="Black" BorderThickness="2" AllowDrop="False">
        <TextBlock Text="Lots and Lots of text..." TextWrapping="Wrap" FontSize="16" />
    </ScrollViewer>

When I run the app, the scrolling is laggy. I am not sure why this is, but I assume it has something to with running at the same time as the xna. Any ideas as to why this is happening? Is there a better solution?

Maybe Cache="BitmapCache" helps you