The lack of performence report about some big site based on django or djangobb is a problem. So please make a test, like maybe 10 thousands topics to show the result or compare to some other apps based on PHP maybe.
And if you would like to compare the speed of the forum DjangoBB with some other forums, then maybe we'll do that later, but so far we do not have a stable version DjangoBB. We're working on it