There seems to be a conflict between SS and the latest Google toolbar. It shows when you click for a one page preview in IE. Even on a very fast machine it can take up to a minute for IE to produce the expected page. Everything is arrested while it tries although eventually it happens.
This first showed up about a week ago when I got the Google notice that it had updated my toolbar(no way to turn off auto updates). It added some buttons.features I did not want and I disabled them using the Settings of Google. The SS problem occurred. I used a Windows restore and everything in SS went back to working fine. Today that notice from Google again. Tried restarts, etc. to no avail. Uninstalled Google toolbar and problem is gone without any restore so it is the revised or updated bar.
Others might be hitting the same grief so thought you should know.

Thanks for the tip, Bob.

I noticed that slowdown too (preview takes a few seconds for me now on a slow computer; previously it was instantaneous). I have been playing with a virus checker and firewall too, so I have been blaming those.