When zombis attack you in hordes they suddenly stop and the jump net to you. It's not a lag issue because the FPS keeps always at 80 more less.
Steps to reproduce:
1. Spawn a bunch of zombies
2. Hit some of them
3. Run away from them but without them loosing your track
4. Wach how zombies stop and suddenly jump near you.
Same issue here,
I have the "Can't keep up!" message of the server on the Development console of the launcher