Same here since Warband 1.151, with my i7-2600, 3.5GB allowed @ NT5.1 32 bits
I feel that the problem is due to blood.
Before on DTV I was able to kill during a 40 bots wave 1 peasant/second, since this patch I have a micro-freeze for each kill, fps drop 85 (VSync+fps_max=85) to 60/30 fps, then I die by the horde after only 3 kills.
This doesn't seem due to ragdoll but from blood.
chadz TaleWorlds killed this game, once again...