I have never had any problem running this game, even with very large battle size caps. I currently have mine set on 700 max battle size for Bannerlord, and mostly high to very high quality with no issues. It can be a tiny bit laggy at the beginning of a battle, but it works itself out pretty quickly. I will say that my comp is pretty good on memory, RAM, processor, video card, etc. It's not the one of the best, but it pretty good for these types of games.
You can turn down the graphics settings to meet your computer specs, so the game will run much better if you need to. All of the settings are adjustable, and there are a few that will definitely increase performance. So it can be modified to fit just about any system qualifications.