When troops bunch up when they rush the gates for example, they enter a horrible tweaking frenzy. Im assuming that the troops are automatically moving to avoid colliding, but it just looks plainly terrible and causes so much stuttering. In Warband the soldiers were simply still if they didnt have a path which they could take, because they werent programmed to "scoot" or "skip" past another soldier that was in their way. I havent been able to find the devs commenting on this specific issue