Yeah, same issue here. My quick investigation found that it could be due to fact game always loading assets from disk, instead keeping them in RAM. So in task manager you can open disk where game installed and see if it constantly reading during game. I've noticed that weapons icon when you select class may slow on load as well when you switch fast after played for while or enemy weapon icon always not instantly appear.
Tried to reinstall nvidia driver (clean install) also make sure shadders folder are clean, so far this didn't help. I had something similar on doom dark ages, where game instead just lag out durring audio delay. Fix there was increase "video cache" or whatever option was called and game was smooth as butter.
For some reason battlefield6 just doesn't like all RAM and VRAM I have and they never fully utilized even when needed, I even have low res textures and low poly LOD models right after new map load every time.
So far I have not found solution.