Unusual lag happening in certain maps for v83

[CloudNine]

I'm using MapleSolaxia source as base but it happens in most sources I've used.

In maps such as ant tunnel there's always usual lags like delays when mobs are killed. Anyone manage to get any fixes or hints of what causes it?

[MentaL]

[Drum]

I remember dealing with something similar when mobs were spawned and killed quickly (bomb mob). It was due to just generally non thread-safe packet transmission code (incorrect handling of the mutex in the packet encoder from memory). That's all I can really remember about it sorry.