First, before anything else, make sure /traceai is OFF. Type /traceai until it says "Do not save homunculus status"
If traceai is left on (with any AI), it will rapidly lag you to hell (this is a game client bug - it doesn't handle the trace file gracefully as it gets larger).
On heavily loaded servers, using a homunculus makes you lag worse - because in homun-lag cases, the "trigger" for the lag appears to be how fast the client is sending commands to the server. I suspect (based on how the lag feels and the obvious paralells) that it's the same mechanism as WoE "queue lag".
I've heard that some maps are getting bad server lag in general this week (as in, bad enough that people with non-homun classes complained about lag on specific map servers), possibly due to activity in LowTI - this could be a contributing factor for you.
In any event - the homun-induced lag is server-side. If you take it to a lightly loaded server, it shouldn't lag. I don't think I've ever seen the AI produce "local lag" (ie, lag caused by the AI consuming too much CPU time - the symptom of this being that the mouse would move sluggishly or not at all), unless /traceai is enabled (and during testing a few times, when i'd screwed up and let it get into an infinite loop).
You can make the lag better by enabling the "LagReduction" option if you need to use homun on heavily loaded map - this mode minimizes the rate at which the AI sends commands, in order to minimize the lag it produces. However, this option will reduce performance (particularly while chasing) on lightly loaded maps - because it's not correcting it's path to match that of the monster as often.
Of course, this is all assuming that your lag is only present with the homun out, since you're directing your rant at me. If you're getting the lag all the time, you should head on over to the tech support section, and we'd be happy to help you out on that.
Edited by DrAzzy, 30 May 2014 - 08:09 AM.