How to make a slider move smoothly...

I'm not sure if that answers your question, but to make the movement of a slider thumb as smooth as possible you can increase the number of steps, as descibed here under Setting Slider Properties.

Hi, Lou -- Thanks for reaching out! In addition to Michael's suggestion, I though I might pass along another discussion that may be of interest: Slider Not Moving Very Easily. 

Hi Lou. This is very old, but some people check these things in the future.

I have a 3-stop slider, but by adjusting steps down to .01, it makes a much smoother, slippery slide.

Your stop settings can stay the same. See image:

I tried the stop method, but now the layers don't show unless you are really precise with where you stop the slider. Were you able to solve that with your step method?

Don't show the layer when the slider is equal a specific value. Show it when the slider is between two values (between .8 and 1.2 is easier to hit than 1).