Don't get me wrong, everybody! I don't want to say the game doesn't have performance issues, it sure does.
At first it was almost unplayable for me, but I got it running perfectly fine on a Windows 10, 1050TI, i5-3570 3.4GHz with 8 GB DDR3 after tweaking with Windows (not the game settings, that didn't help). However, I use a SSD.
I just want to help everyone reading this to enjoy the game as it is right now. Here is what did the trick for me:
The obvious - deactivate as many adds in the background as possible (sorry, of course you do). ?
Especially deactivate Realtek Audio. Windows 10 and Realtek don't like each other.
Disable NVIDIA High Definition Audio in the Device Manager.
Uninstall GeForce Experience.
Turn off or uninstall Cortana.
Run Steam in -no browser mode ["C:\Program Files (x86)\Steam\Steam.exe" -no-browser -applaunch 261550] (-applaunch 261550 starts Bannerlord)
In game settings I use:
Display Mode: Borderless Fullscreen, Screen Resolution: Desktop Resolution (I turned my desktop resolution down to 1600x900 for this), Frame Limiter: 30, all Shadow and Particle options at Low/None, and the Sound settings as low as possible. The rest is set to medium, with most of the on/off options turned off.
Hope that helps someone. For me it turned the game from almost unplayable into fun with 500 men sieges.
Best regards and stay healthy.
[EDIT] How to use Steam's no browser option (just in case):
Create a desktop shortcut (copy Steam shortcut for example, but don't copy Bannerlord's icon, it won't work)
Right click the new icon and select Properties. Replace the Target entry with the following line:
"C:\Program Files (x86)\Steam\Steam.exe" -no-browser -applaunch 261550
Restart your PC and don't log in to Steam right away. Use the new icon to start Bannerlord and log in to Steam when asked to.
(On some PCs Steam somehow uses a lot of ram. I mean a lot a lot. This might be the most effective step of all.)