Okay, just reporting:
(note: the lag I'm talking about is not the all-around poor fps Halycon et al are talking about, afaik)
When I'm on a horse, about half the time when I approach an enemy, especially a foot troop, the game lags terribly. As in, a good four or five seconds of me and my horse just randomly skipping around all over the place. Rubberbanding or ice-skating or whatever you want to call it.
This still happens when I have everything on lowest settings possible. 800x600, everything at 0%/off, LOD disabled, everything. My FPS stays pinned at 200 (my max setting) ALL the time.. except this one particular scenario (horseback, near enemies). It usually happens the worst when I actually touch an enemy with the horse itself.
I tried to fraps it, but fraps causes just enough lag by itself to make it hard to distinguish. Still tinkering with it though, so..
If I can get a good vid of it I'll file a bug report on the tracker.