title: button.mouseHover change button background image slow
body: <p>I have written some code to change a button's background image on mouse-hover, however when the image is changes it seems that it is a bit slow to complete.</p>
  
  <p>That is, the process of setting the new picture as its background image is slow. By slow I mean a few milliseconds, but still enough to be seen! </p>
  
  <p>Is there anything I can do about this, to speed up this process?</p>