Mouse isn’t smooth always jittery

We receive more questions about Rainbow Six Siege than any other game because the game's aim/look engine is so poor. That said, you can make it better by dialing it in for your mouse and your style of play. Before you make any changes, it is important to read this understand how the mouse and keyboard work through this device, and you understand the limitations that effect the way the movement feels, especially on R6S with it's low maximum turn speed. You are basically fighting both a maximum turning speed and a resolution smoothness issue which you feel when aimed down sights and moving very slowly. Please read through all of this for maximum benefit.

Now to start making improvements in R6S you will need to begin by testing the polling rate of your mouse with the game. R6S for some reason plays smoother on some mice when you REDUCE the polling rate of your mouse. Some mice seem to work better at 500Hz or even less, but you need to test the different polling rates of your mouse to see what feels best to you. Keep in mind, this isn't going to completely fix it but will make it feel a bit better so you can start making additional changes from there.

Next, R6S has two control modes, Classic and Updated. You will need to try them both to see what you like, but remember to make the changes to the in-game settings shown on the download page in the K2 App.

Once you find a mode that feels better to you, you will need to make sure to adjust the mouse speed in the K2 app so that you are not exceeding the games maximum turning speed as described in the link above. R6S is one of the few games were you need to really pay attention to how fast you move your mouse, as unlike COD or Battlefield games, R6S will allow you to reach maximum turn speed very easily and the faster you move your mouse, the slower you will turn. It is a fine line here of learning the game's maximum speed so you reach peak performance without penalty.