My biggest issues with lag are definitely tied to certain assets, in .2 early on I would get serious lag problems(sound and fps performance hits) I cured them by updating my audio drivers. The assets I had the most trouble with were hawkmoths and harassers, I knew immediately when either spawned on the map.
Post .3 the same issues are back with the same assets. I updated my drivers (audio and video this time) and performance improved to a playable state but not necessarily an enjoyable one.