if you run with multiple people and kill many mobs at the same time, like for example in the screen (groto)
this will cause lags for all players in the group. the more players are in the group (it triggers for everyone I assume), the more lags it produces.
I think the internal script will update the number for each killed mob (not only 1 time in a second or so) and this I assume cause heavy lags
Greetings