In my opinion the speed should be reduced, they should still be faster than humans but not as ridiculous as they are now. The zig-zagging should also be fixed and I think that if you are running from them and your somehow get out of there vision or a certain distance away that they should stop chasing you, it makes no logical sense that you run through 4 buildings, make it into the forest and then 30 seconds later 40 zombies are hauling ass directly at you.