Not anything that's available. You'd need a script that queries the last post time for every forum, and then go through every user and update FORUM_LAST_VISIT table for each user/forum.
Another thing I noticed is that your ft_min_word_len is set to 2 characters. The default MySQL is 4, they say 3 can be unstable, I imagine 2 is pretty drastic. Basically, MySQL is indexing every word that contains at least 2 characters, so this probably doesn't help matters when things get busy.
