Adding Inlines to TextBox is very slow

Question

In my application i have a console-like-control that displays infromation I send from various functions using:

Run run = new Run("FancyText");
run.FontSize = 15;
run.FontFamily = new System.Windows.Media.FontFamily("Consolas");
run.Foreground = FancyColor;
tbConsole.Inlines.Add(run);
tbConsole.Inlines.Add(new LineBreak());

However this slows down my programm drastically after adding a lot of textboxes. Am i doing something wrong or is this just what you can expect? (By the way if i instead of the adding Runs to the Textbox i use a Stackpanel and add Textboxes it works fine and fast)

Answer 1

I have never been able to get this to run as fast as i wanted so i came up with a different approach which complies to MVVM. I created a virtualized stackpanel to contain textboxes that i create and add in code:

 <ScrollViewer Grid.Column="2" Name="consoleScroll" Background="Black">
    <ItemsControl  ItemsSource="{Binding Log}">
       <ItemsControl.ItemsPanel>
          <ItemsPanelTemplate>
             <VirtualizingStackPanel/>
          </ItemsPanelTemplate>
       </ItemsControl.ItemsPanel>
    </ItemsControl>
 </ScrollViewer>

Code:

public ObservableCollection<System.Windows.Controls.Control> Log
{
    get { return (ObservableCollection<System.Windows.Controls.Control>)this.GetValue(LogProperty); }
    set { this.SetValue(LogProperty, value); }
}

// Using a DependencyProperty as the backing store for Log.  This enables animation, styling, binding, etc...
public static readonly DependencyProperty LogProperty =
    DependencyProperty.Register(nameof(Log), typeof(ObservableCollection<System.Windows.Controls.Control>), typeof(ViewModel), new PropertyMetadata(default(ObservableCollection<System.Windows.Controls.Control>)));

//Code to call in a function
TextBox tb = new TextBox();
tb.Foreground = new SolidColorBrush(Colors.Hotpink);
tb.HorizontalContentAlignment = HorizontalAlignment.Left;
tb.Text = "my nice string";
Log.Add(tb);

The resulting console window works as expected and supports multi color. Needed to censor parts of it...