Pixie Scheme uses quite a lot of computer power when something is being evaluated, so not much is left over for any desk accessories and other applications that may be running. You can encourage Pixie Scheme to give more time to other tasks by checking the "Scroll Often" option and unchecking the "No Window Output" option. Pixie Scheme will then relinquish some extra time whenever text is output to the Pixie Scheme window. (Pixie Scheme will also slow down a great deal.)