When I post to a thread, the discussions page isn't allways updated to reflect the changes (the message count isn't increased).
It doesn't bother me, I just thought I'd let you know in case you weren't aware of it.
Also when the message count in the index page is updated (I exp. after 1-2 minutes of posting), updation is unsynchronize. Either of server BEA/Oracle9i is updated later.
At the moment the discussions page uses oscache, to cache the page for a few minutes. This has really helped performance, as we aren't dynamically creating the page all the time, instead we can just serve a cached copy.
In the future we will be able to use our own caching policy, so we can mark the cache dirty when a post is made to a forum.