Oh thats right. You could add a backbuffer when creating your graphics to eliminate the flicker. This is VB.NET but it should be simple to change to C#.
VB Code:
  1. Me.SetStyle(ControlStyles.DoubleBuffer, True)
  2. Me.SetStyle(ControlStyles.UserPaint, True)
  3. Me.SetStyle(ControlStyles.AllPaintingInWmPaint, True)
  4. Me.SetStyle(ControlStyles.ResizeRedraw, True)
  5. Me.UpdateStyles()