Are you using it on chromium? It's the only browser I get raw mouse events from right now, so other browsers tend to be more choppy.
As for the habits, the point of this program is that it ultimately admits that far domain transfer for aim trainers is difficult regardless of what you do, so it tries to optimize in an absolute sense your motor control over your mouse. That way, regardless of scenario you'll have smoother and more efficient aim.
Yeah I tried Firefox and Chrome
EDIT: Maybe take some inspiration from Three.js? This demo works fine for Firefox and Chrome with a nice, smooth cursor that I'm used to https://threejsdemos.com/demos/camera/first-person
Firefox is definitely choppy for me renderingwise. I use Vivaldi which is Chromium based and the only choppiness comes from the friction of my sweaty wrist on the gamepad. If I hover my wrist and only let it basically rest on the mouse itself, tracking becomes smooth. Changing my hand motion and stance is definitely part of the training process to become a better player.