Seeing how the page seems to be taking a lot of bandwidth, I'd like to suggest the use of png instead of png. As an example, I have uploaded pe_logo.gif, converted to a 32-color png:
png:
gif:
The size of pe_logo.gif is 5750B, while pe_logo.png only needs 2678B.
Another idea (suggested by a friend) would be to set the expiry time of the static pages to perhaps one week in the future, so browsers don't download them every time but instead get them from their cache.
I don't think changing the gif to a png will help much, but png is the better standard anyway so I think it would be a good idea anyway
As for saving bandwidth, using last-modified, etags and other headers effectively will lower the bandwidth and other resources enormously.
Another nice option is showing everything on the problems page by default and making the solved/unsolved/sort settings completely in javascript so it won't require a page reload
By combining this with a cookie update once you solve an issue will make that page completely static so it only has to be loaded once per new problem per user. This would most likely be the most rewarding change possible, it would remove the possibility to hide the "last post" and "posts" columns from users that haven't solved it yet (or the other way around, not visible for anyone).
