Path Performance Issues in Silverlight

So I was talking to Jared and Devin and the other designer/integrator types this morning and some one pointed out that when you create a Path that uses stretch and has a height and width Silverlight takes a huge preformance hit. Not sure why this is as it doen'st appear to be an issue in WPF that I know of but it seems to be a 'don't do that' in Silverlight...