WPF PathGeometry update is _SLOW_

Answer 1

If you don't need hit testing, context menus, tooltips for your curves, you can use simple visuals instead of framework elements.

Answer 2

1- I would try to use StreamGeometry:

        StreamGeometry streamGeo = new StreamGeometry();
        Stopwatch sw = new Stopwatch();
        sw.Start();
        for (int i = 0; i < 10000; i++)
        {
            streamGeo.Clear();
            var ctx = streamGeo.Open();
            ctx.BeginFigure(new Point(0, 0), false, false);
            ctx.QuadraticBezierTo(new Point(10, 10), new Point(10, i), true, true);
            ctx.Close();
        }
        sw.Stop();
        Console.WriteLine(sw.ElapsedMilliseconds); // For 10k it took 30 ms

It looks much faster than PathGeometry+PathFigure.

When you set the Point for the QuadraticBezierSegment it recalculates everything. That's why it is slow. And more slow when it is already added to a geometry.

2- Try to use only 1 frameworkelement for all of your curves. Check this: Writing More Efficient ItemsControls

Answer 3

I would imagine that your performance issues come from descending from FrameworkElement and having the WPF layout engine recompute the layout as the curve is computed.

What you can consider is to model the curve by descending from Freezable and then use a FrameworkElement (like PathGeometry) to display the actual geometry.