title: Performance problem with multiple ItemsControl inside a ScrollViewer
body: <p>I need a single scrollable surface that contains two bound lists. At first, I used a ScrollViewer with two ListBox inside, each having their scrolling disabled, so I could still have item selection. Seeing the poor loading time performance, I changed my ListBoxes to ItemsControl, but the performance is still terrible. In total, my two lists have only 110 items.</p>
  
  <pre><code>&lt;ScrollViewer Grid.Row="1"&gt;
      &lt;StackPanel&gt;
          &lt;Button Style="{StaticResource EmptyNonSelectButtonStyle}" BorderThickness="0" HorizontalContentAlignment="Left" Click="AnyCityButton_Click"&gt;
              &lt;TextBlock Text="{Binding Resources.CurrentLocationItem, Source={StaticResource LocalizedResources}}" FontFamily="{StaticResource PhoneFontFamilyNormal}" FontSize="{StaticResource PhoneFontSizeLarge}" /&gt;
          &lt;/Button&gt;
          &lt;TextBlock Text="{Binding Resources.TopTenCitiesHeader, Source={StaticResource LocalizedResources}}" Style="{StaticResource PhoneTextSubtleStyle}" Margin="12,12,12,8" /&gt;
          &lt;ItemsControl ItemsSource="{Binding TopTenCities}" ItemTemplate="{StaticResource CityDataTemplate}" HorizontalContentAlignment="Stretch" /&gt;
          &lt;TextBlock Text="{Binding Resources.TopHundredCitiesHeader, Source={StaticResource LocalizedResources}}" Style="{StaticResource PhoneTextSubtleStyle}" Margin="12,12,12,8" /&gt;
          &lt;ItemsControl ItemsSource="{Binding TopHundredCities}" ItemTemplate="{StaticResource CityDataTemplate}" HorizontalContentAlignment="Stretch" /&gt;
      &lt;/StackPanel&gt;
  &lt;/ScrollViewer&gt;
  </code></pre>
  
  <p>What can I do to improve performance? I've tried setting the ItemsSource after the page loading, but it still ugly (empty lists for a few seconds), doesn't make more sense.</p>
  
  <p>Thank you.</p>