Netflix Streaming seems choppy after installing Silverlight 2.0 on Mac and PC

While watching Netflix Instant Stream via my Roku box or my Xbox, the picture is fluid and smooth. I have noticed that since installing Silverlight 2.0 on my Mac and also my netbook (which is Windows XP), the picture freezes for a split second every 5-10 seconds, resulting in a very jerky picture. I also have Verizon Fios 20mps, so I am sure it is not my ISP. Has anyone else noticed that films they watched on their PC prior to Silverlight 2.0 had a much smoother framerate then before installing Silverlight 2.0?