"changed the thumbsticks". Could you elaborate on that? You mean swapping the thumbstick hardware, or changing a control setting?

I bought new thumbsticks, the old ones were slowly losing their rubber grips. At the same time it fixed the whole 'slow right motion' problem. Have you compared the problem on another game? If you have slow movement on a different game then it must be your hardware.

I haven't noticed slow movement on other games. Thanks for the advice.

The hollow in the middle of the stick that the mechanism sits in gradually wears and gets larger, making your thumbstick feel "loose", and meaning that when you pull the stick all the way to one side, the actual mechanism doesn't go quite that far. But TBH, if you've worn a stick out that bad, chances are the rest of the pad is equally clapped-out. If I do repair a pad, I replace the sticks, stick mechanisms, rubbers and switches all in one go. All the parts are cheap and readily available, and the sticks and rubbers can be done without soldering. Stick mechanisms are the same package for each console, but their response curves are different: while you can put Playstation mechanisms in an Xbox, and vice versa, you don't want to because it will drastically alter how the stick responds. The triggers are hall-effect sensors not pots, so the mechanism works without anything touching anything and there's nothing to wear out.