C# Revit Extension using WPF & SharpGL

Question

I'm trying to create a Revit Extension using SharpGL in WPF window and just can't get the FPS over 10. WPF & SharpGL work smooth together without Revit. This is the simple code

public class Class1 : IExternalCommand
{
    public Result Execute(
      ExternalCommandData commandData,
      ref string message,
      ElementSet elements)
    {
        System.Windows.Application app = new System.Windows.Application();
        app.Run(new MainWindow());
        return Result.Succeeded;
    }
}

Revit Execute runs WPF's MainWindow, which draws nothing at 10FPS!

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void OpenGLControl_OpenGLDraw(object sender, OpenGLEventArgs args)
    {
        OpenGL gl = args.OpenGL;
        gl.Clear(OpenGL.GL_COLOR_BUFFER_BIT | OpenGL.GL_DEPTH_BUFFER_BIT);
    }
}

Is there a way to smooth it up, or should I just stop using SharpGL and go with WPF?