Some of you might already tried this, it adds one line"borderless_window=true" in the .cfg and changes windowed to true. This makes strategic and battle maps go alot smoother. Credit goes to the team of stainless steel 6.3.
Not troughly tested yet but so far campaign and custom battles works. but just in case make backup of warhammer.cfg,
You might have to alt tab out and in when you start, because it runs in windowed from start.
Let me know what you think
Edit. ok since you cant upload .cfg
Change this in warhammer.cfg in medieval II total war/mod/call_of_warhammer
windowed=true
And fill in under to
borderless_window=true
and save.