Maybe it's the ads that load the page much slower, but the "left off" script seems too slow. When I use the back function into the main page, it takes a long time for the page to situate back to the post where I clicked on.
Along these lines, is there a way to highlight new posts? Long threads like those in the political board are hard to follow when you can't see where new posts start or end.
Lastly, a suggestion, how about a "reply to your post" email alert?