I guess this is for whoever comes after, but since couldn't find an update to this post anywhere else. First, the interface seems to be slow to respond. This is because the event structure is located in the state handling loop. You might want to consider placing the event handler in a separate loop that is used strictly to handle such interactions. Second, you are using waaaaaaaaaay too much CPU - throttle that loop (10 ms should be fine). Finally, consider using the elapsed time express sub VI instead of your own VI - this will save time and energy.