I find the performance increased greatly, however the zombie's detection of players is broken in my opinion. When crouched and running in grass would normally attract zombies from 30 to 40 meters away, they now seem to agro from 100 to 150 meters away. They also seem to still hear pretty damn well in buildings. I stopped playing after one zombie came running at me from about 300 metres, hit me once, I passed out and it ate me while another zombie was watching it happen without any interest. I was at 8500 blood before I got hit.