The Threads look and feel is
vastly different from UBB - your users might not react well to the change. (Threads 6 is going to have a nifty templating feature, far better than the one UBB has... perhaps someone will come up with a UBB skin in the future?)
You appear to have the Accelerator enabled, and it is using zlib compression... Log into your control panel - how many of your total hits are coming out of the cache? If it's a somewhat low figure (< 50%), a small hack can add zlib compression into the UBB scripts as well...
If you don't like the idea of hacking, I have a few general tips.
1) Use the lowest values for topic and forum pages possible, i.e. 15 posts per page.
2) Disable the reply iframe.
3) Run all the graphics you've added through an image optimization program or service
4) Run your server log files through a hit tracker... most reputable hosts include this in their hosting plans. It should tell you what URLs are hit the most and where major bandwith is being transfered.
--
Charles Capps
Programmer, Infopop Corporation
Please do not contact me privately for support - post on the board or open a support ticket instead!