It's hard to say without code. An issue could be that you need the screen to update and instead of updating only a part of the screen you update all of it. For this you could look into
Control.Invalidate
.
http://msdn.microsoft.com/en-us/library/system.windows.forms.control.invalidate%28v=vs.71%29.aspx[
^]
Another big problem might be that you load the image from resource to display it and then discard it again immediately, meaning it would need to reload every time. Instead you could load it when the application starts, keep it in memory and use that.
Good luck!