Howdy,
It looks like the Live Comment Preview causes unexpected API calls to Akismet – a separate API call each time the preview updates (i.e. almost every keystroke).
I assume this happens because the preview plugin calls the pre_post filter, which in turn triggers bb_ksd_check_post().
I imagine there may be other plugins that cause a similar problem. Would like to help fix it but I have only a superficial understanding of the bbPress code. Suggestions for the Right Way to do it?