How many hz is the mouse getting polled? sorry should have specified.
I guess dpi, mouse polling hz, and fps can have an impact. Screen size, fov and hz should not have any impact on that floaty feeling.
I guess lower DPI will work betterm 800 is fine though. But if you use something like 2000+ maybe try lower settings, and raise sensitivity ingame. Also the polling rate could have a huge impact.
Btw not sure if its placebo effect, but this one helped my aim a little.
MarkC Windows Mouse Acceleration Fix
So far, what I can tell from my experience, with laptop and now a better pc …
The cpu was the bottleneck, and that made my input lag the most.