Yeah, it's odd how different browsers are faster at one thing, but slower at another. meh.
Sides controls the number of sides on the carousel. Four for a cube, etc. Odd numbers work, but look a little funny since I can't do perspective and the rotational axis isn't obvious/visible (something to work on). Since only the front of the carousel is shown, there will be sides/2 images on screen at a time.
Steps set how many intermediate steps are used in moving a picture one position forward. Say we had steps:16, then if picture-A is at the front, there would be 16 repositionings before its neighbor picture-B is in front. Too few steps will make the movement jerky, but will save processor power. More steps is more taxing, but smoother. Way too many steps will give a vibrating sort of look, due to rounding error and the finite size of a pixel.
I like steps*sides of around 100-140. Gives a decent balance of smoothness and processing load.
At the moment, speed doesn't take into account the number of steps (more steps will slow down the overall spin). I'm working on making the speed more independent; still trying to find a scheme I like.
Edit: The carousel will now spin at a revolutions per minute rate roughly equal to the speed parameter. Due to differences in processing load, the same speed with different numbers of steps will result in slightly different net speeds (I've tries to compensate but machine/browser variances matter).