Bushi, jb: Maybe I'm way off here (and if so, I apologize) because I'm not all that experienced in using python & Tk (at least like this). Wouldn't your script still run "free" if instead of a "go" button, you had the processing part of the script tied to a "mouseUp" function that was part of the slider move? What I'm getting at is, if you wanted to, the "go" click could be eliminated and still save processing cycles. You move the slider with a mouseclick, and when it's released, the update is initiated. Haven't tried it, just a thought. I didn't have time to look at or code this myself. --