There is something nice i found on Warhammer Alliance on how to improve your performance/fps in big scale fights (i.e. sieges, city raids and szenarios).
I heard that disabling the combat log will increase performance in large group situations(IE, keep raids). I found this script which doesn't make the combat log box go away, but stops all combat text from being printed into it:
/script TextLogSetEnabled("Combat", false)
Setting false to true makes it turn back on. Will the performance boost only occur if I completely delete the combat tab, or will just making the text not be written anymore be enough?