I am trying to make my game more accessible to lower end users, would switching to R6 increase performance for those users or would the difference be negligible?
R6 would run better for sure, But R15 only takes like .001 fps(retrospecting to the fact that it only takes a few fps). R15 animations are more detailed but yeah.
The performance increase would be negligible for the negative impact it can have on the detail of your game.