no more details needed, I can already very easily tell you the problem, you have an outdated system.
8gb of ram is even if barely, usually enough. Having a bit higher might help with some stutters, especially if you have background applications open.
Your main "problem" is the cpu. It is an old and slow cpu by todays standars, and bannerlord (as almost every game) doesn't make full use of 6c/12t, so speed matters much more. Your system is greatly bottlenecked by the cpu when playing bannerlord, the gtx 960 is also now a bit old and not that fast, but it's fast enough for Bannerlord in 1080p to keep up and exceed what your fx6300 cpu can handle. So no matter what graphical settings you change, your performance is determined by what your cpu can handle, and the settings don't effect that much.
Try lower battle size, lower sound channels and maybe disabling things such as cloth animations. But if you need better performance, most significant thing you can do is get a better cpu. Obviously will need a new motherboard and ram for that as well, if you can afford it go with 16gb to not have ram problems.
Also try closing every background application, browsers such as chrome/edge etc. take up a lot of ram, might also cause performance drops