Those times don't sound unrealistic, given the numbers here Historical data . I'm also seeing 4-5 minutes to tack with that wind, losing a couple of ship-lengths. Of course, for a game it makes sense to be towards the snappier side of realistic.
Things to try would be reducing wind drag and increasing water lift coeff, both say by 0.1, and maybe increasing griping to 7.
(I also notice that the helm is incredibly slow when ordered to simply turn - I should set it back to the standard speed.)