I have cable modem access and have a terrible time with Renderosity.  In fact, I gave up on it for a while.  It reminded me of ancient dial-up speed and it was too irritating to navigave.  I came back hoping to find it better but it seems even worse.

One thing that makes it much more annoying is that I have tried bookmarking the forum page or other pages I want to revisit to make it faster but it doesn't help - whatever I bookmark, I still have to go to the first page!  Then I tried leaving the page I want open while I do other things, so I can go back to it but after a while it automatically goes to the main page again!