WPF - UserControls very slow

Question

I am designing something similar a PropertyGrid where I want to show properties of objects. For special reasons I am not going to use the PropertyGrid but create my own.

For each property I have created a custom usercontrol. Now to my horror the performance is very bad. If I have something like 100 properties it takes 500 milliseconds to show them in a StackPanel/Listbox.

I did an experiment where I add 200 default UserControls to a StackPanel. It took about 50 milliseconds. Still a very high number I think.

Should I not use usercontrols for such a purpose? It seems very object-oriented to do it this way and I can not really see another solution.

However I can see that PropertyGrid and TreeView performs good, so what have they done and what should I do?

Edit:

        Stopwatch stopwatch = new Stopwatch();
        stopwatch.Start();
        using (var suspend = Dispatcher.DisableProcessing())
        {
            // Add all children here
            for (int i = 0; i < 200; i++)
            {
                this.propertiesStackPanel.Children.Add(new System.Windows.Controls.Button(){Content = "Testing"});
            }
        }
        stopwatch.Stop();

This still takes about 50 milliseconds. If I change to my own custom usercontrol it is much higher. I might add that scrolling is not a problem.

Edit2:

OK. It has nothing to do with stackpanel. I have found out that it is because creating UserControls is a very expensive operation. If you have any other idea of what to do I would gladly hear them :)

Edit3: Nothing is going on in the constructor of my usercontrol other than InitializeComponent method. Here is an example of a usercontrol I am adding.

<UserControl
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
x:Class="PropertyBox.GroupUC"
x:Name="UserControl"
d:DesignWidth="640" d:DesignHeight="480" Background="#FF32B595" BorderThickness="0">

<Grid x:Name="LayoutRoot">
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="20px"/>
        <ColumnDefinition Width="*"/>
    </Grid.ColumnDefinitions>
    <Border x:Name="border" BorderThickness="0,1" Grid.Column="1">
        <TextBox Text="TextBox" TextWrapping="Wrap" VerticalAlignment="Center" HorizontalAlignment="Right" BorderThickness="0" Padding="0" Visibility="Hidden"/>
    </Border>
    <Label x:Name="groupNameLabel" HorizontalAlignment="Left" Margin="5,0,0,0" VerticalAlignment="Center" Content="Label" Padding="0" Grid.Column="1"/>
    <Button x:Name="expandButton" HorizontalAlignment="Left" VerticalAlignment="Center" Width="12" Height="12" Content="" Click="ExpandButtonClick" Margin="4,0,0,0" Padding="0" Grid.ColumnSpan="2" d:IsHidden="True"/>
    <Image x:Name="expandButton2" Visibility="Hidden"  Width="12" Height="12" HorizontalAlignment="Center" VerticalAlignment="Center" Stretch="None"/>
</Grid>

Answer 1

My suspicion is that you're triggering many layout updates while adding your hundreds of children.

If that is the bottleneck, you may want to consider doing:

using(var suspend = Dispatcher.DisableProcessing())
{
       // Add all children here
}

This will cause the dispatcher to stop processing messages while you add your controls, and do the entire layout and render in one pass at the end.

Answer 2

If you find that creating many UserControl s is too expensive an operation, what about a solution where you don't need to create UserControl s at all?

I'm by no means a WPF expert, but what about using data binding a ListBox or ListView against a list of objects each of which represents one property of the object under inspection? Instead of a StackPanel , you'd have a Listbox or ListView ; instead of UserControl s, you would define one or more DataTemplate s.

---

Basic code example:

Define a type that represents an entry in your custom property grid; for example:

public namespace YourApplication
{
    public class Prop
    {
        public string Name { get; set; }
        public Type Type { get; set; }
    }

    public class Props : List<Prop> { }
}

Then, in XAML (I can't currently check this for 100% correctness, but hopefully you get the idea):

<Window ... xmlns:local="clr-namespace:YourApplication">
  <Window.Resources>
    <!-- this Prop list serves only as a demonstration in the XAML designer -->
    <local:Props x:Key="somePropsForDemonstration">
      <local:Prop Name="Name" Type="System.String" />
      <local:Prop Name="Age" Type="System.TimeSpan" />
    </local:Props>
  </Window.Resources>
  <!-- here's your StackPanel replacement; bind it to a real items source -->
  <ListView ItemsSource={StaticResource somePropsForDemonstration}>
    <ListView.ItemsTemplate>
      <!-- this is a UI template that defines how a Prop object gets displayed;
           together with the Prop type, it replaces your UserControl -->
      <DataTemplate DataType="local:Prop">
        <StackPanel Orientation="Horizontal">
          <TextBlock Text="{Binding Name}" FontWeight="Bold" />
          <TextBlock Text=": " />
          <TextBlock Text="{Binding Type}" FontStyle="Italic" />
        </StackPanel>
      </DataTemplate>
    </ListView.ItemsTemplate>
  </ListView>
</Window>

I seem to remember that there are ways to have "polymorphic" data templates; ie. depending on a property's type, you could use a different sub-class of Prop and also use a different data template per item type.