100% CPU load by DNS on Mikrotik RouterOS 6.33.3

A couple of days ago my Mikrotik 750GL started making lags. In the '/system resource monitor' I got that cpu load was 100%. According the '/tool profile' it was made by 'management' and 'dns' services. Auto update script had failed for some reason. Solution was to update to 6.33.5 manualy.