Well boss kill speed isn't super important, while DH kill bosses pretty quickly especially if you slot Single Out, a WD could probably kill it twice as fast with the right items and the same paperdoll damage with a pet build and using fetishes+slam dance voodoo totem+wrathful prot gargantuan. Doesn't really mean all that much, elites kill speed is more important imo and elites tend to have a lot less hp than bosses so the strong burst of a crusader is sometimes good enough to kill them near instantly.