I think that I have the same problem. Fps are fine but the mouse seems indeed "laggy". I suspect a frametime issue but can't acctually test that since Bungie doesn't allow 3th party programs (as far as i know) What are your pc specs ? I'm on Ryzen 2700x Nvidia 1080 16GB 3200mhz Game is installed on ssd
I have the exact same issue. Check your cpu usage, as I believe that is the cause. I am unaware of what causes the cpu usage though.