With the recent upgrade of SBS, we now have the mini-RTE in the forums. However, posting an reply from the mini-RTE is noticeably slow. Here's what I usually do:

1) Open a discussion
2) Click on Reply
3) Mini-RTE window opens inline quickly (no problem here).
4) Type in a reply (even a single line is enough)
5) Submit the post. This takes extremely long. The "Posting Reply" message is shown and the post submit takes a minimum of 7-8 seconds to complete.

Attached are a few Firebug screenshots that show what's going on when the Submit is in progress.