Ahh, okay. I've been able to get around it by turning down battle sizes back to 100 (heh).
I have to say though, something about combat in this mod definitely is making it more fun than native for me. I think it may be the formations the troops try to stay in (I think I saw that as one of the enhancements?) I've also tried (for the first time) having a mostly horse archer/skirmisher force. With that, in combination with the way the enemy behaves, battles usually turn into these awesome slow paced skirmishes where waves of enemies charge my own lines. Only a few tend to make it far enough to actually melee (and I'm usually parked on a hill :p), but generally enemy attacks tend to get more intense with time as my men struggle to "catch up" with finishing off the last wave before the next gets within range. (I like being outnumbered in a fight.)
But the most fun is how I'm able to simultaneously part-time lead my forces (relocating them to different defensive areas, initiating an overwhelming charge on occasion to finish off the last wave before the next arrives, etc) while also riding out alone or with one or two other audacious horse archers doing the same on occasion. (Not sure if that's an AI bug or what but it really makes this style of combat more fun, as a few of us go out to delay 10-30 enemies on our own in close combat, meanwhile there's dozens of horse archers sitting back putting arrows into them...) Definitely makes it a challenge when you make it a priority to rescue your braver troops who managed to get tangled up in the enemy's formation.
Probably not unique to the mod, but it works well with the troop types available.
I do like the setting, though, a shame we don't have the source now.