Erhm, actually the magic solution number 20, is to start a new ToB game, importing a save not required but suggested, nothing more... as that should remove few of the lag producing script variables from all the games, don't ask me why, it wasn't me that discovered this...No, I meant exporting the whole game and reimporting though frankly, I don't know exactly how that's done. I've just seen folks cite it as a "solution" to laggy issues like this where you've removed the source of the lag but it won't go away.
And if it still lags, try the other 22 solutions in the answer #5.