If the rate itself hasn't changed, *something* certainly has. I can attest that whenever I see a necro/wererat/werejackel, it always will have filled the entire room it's in as well as start filling in spaces behind me (in the corridor outside) by the time I can step towards it 2-3 times. Just spent 40 in life minutes trying to kill a necro in prerelease 8, but because of monsters swapping places and summons, I was unable to kill him, despite him standing in just a 4x6 room.