Flux costs and action time decrease with (current loop) stat value, though there might be a lower bound at around 2 flux/action (I haven't gotten past that for Do Makeup even in the high ten thousands)
Your stat value is very visible (it's the left number on your stats), but the current flux costs are not displayed anywhere I know of. I'm measuring it by counting how many times an infinite repeat action happens in 10,000 flux