It surprises me that you had server issues. My board has the exact same shoutbox. While my usual traffic is maybe 20-50% of what TFP's is, I notice almost no server lag. We have something like 175,000 shouts logged so far.
My board is even on a shared server.
If you are interested in discussing any of the specifics, or ways to maybe sort out the issues, let me know and maybe I (or some of the techie admins from my board), can help.
