Tiver: That's inaccurate, if the FPS is low the mouse movements should just appear jumpy, not actually move slow. It's simple enough for the game to track how much the physical mouse has moved in between frames. If the FPS did affect it the that is a horrible bug where something is capping the movement per frame.

I however don't have FPS issues or lag issues, I am having sensitivity issues. Moving the mouse 1" physically equates to too small of a movement on screen. The amount it moves on screen with the smoothness shut off perfectly reflects how much I move it physically, regardless of the speed at which I move the mouse. The problem is you can't adjust what the amount it moves on the screen is and with my mouse that amount is far too small.

I imagine I could buy a mouse with a higher sensitivity or one of the ones that lets you adjust the mouses sensitivity and solve my problem that way, but it's simple enough to code in a UI sensitivity problem and just solve this in the game like many other games have.

Tiver: Explain why that would be the fact, I'm not even sure what you mean by "software mice", all mice are hardware. Then there's the OS with drivers that tracks the position data from the mouse, then there's software that uses it. Any decent game is going to have Input processing happening independent of the video end of things. The FPS will alter the lag and rate between making a movement and seeing it on screen. If it affects the actual rate the mouse moves at then that is a horribly coded piece of software. I can think of no game that has done this.

It's very simple to decouple the framerate from the rate at which it polls and handles user input. It's considered a best practice by us programmers. I think your understanding on this subject is limited. It's certainly possible for poor programming to cause a link between FPS and mouse speed, it's just extremely rare as it's a very poor design.