Creatures do not stop chasing character

After exploring different cells without killing creatures when I return to one of them all creatures that I previously encountered run in my direction to attack me. In those cells there is also huge frame rate drop. F3 shows that this is physics problem. It might be related to #3410 (closed).

(RM-3476 from redmine: created on 2016-07-24 by Vuko Drakkainen, , relates #1930 (closed), relates #2172 (closed), duplicates #2567 (closed))