Custom SolidColorBrush too slow when drawing rectangles in WPF/C#

Question

The following code effectively creates a 2D grid of rectangles, my issue is that when I use a custom SolidColorBrush the rendering becomes really slow.

public partial class CalculatorView : UserControl
{
    /// This is how I'm creating my custom brush
    Brush myBlueBrush = new SolidColorBrush(Color.FromArgb(255, 165, 211, 246));

    public CalculatorView()
    {
        InitializeComponent();
    }

    private void buttonCalculate_Click(object sender, RoutedEventArgs e)
    {
        for (int i = 0; i < 100; i++) {
            for (int j = 0; j < 100; j++) {
                RectangleGeometry myRectangleGeometry = new RectangleGeometry();
                myRectangleGeometry.Rect = new Rect(((40 + 1) * i), ((40 + 1) * j), 40, 40);

                Path myPath = new Path();
                myPath.Fill = myBlueBrush; 
                myPath.StrokeThickness = 1;
                myPath.Data = myRectangleGeometry;
                CanvasSheet.Children.Add(myPath);
            }
        }
    }
}

If I change myPath.Fill = myBlueBrush; to use a native brush myPath.Fill = Brushes.Red; the speed improves a lot.

How can I use a custom SolidColorBrush without sacrificing speed?

Thanks

Answer 1

you need to Freeze brush before using it to improve performance. add

myBlueBrush.Freeze();

after InitializeComponent(); in userControl constructor.

Brushes class freezes its brushes after initializing them. see source code of KnownColors.SolidColorBrushFromUint