I just downloaded the Beta viewer for Windows and not only is the lag REALLY bad, but I can't switch to Viewer 2 either. my internet connection is fast and it's completely fine. I've been living with someone who had a bad connection for the past three months so I haven't used SL, but I'm visiting my mom and it worked here before I left. I didn't have Beta, but it still worked fast and great, and I was able to switch viewers.