At this moment there are several HTTP-requests for downloading the default images, like sortedHeaderUp.gif, down.gif, up.gif, none.gif, spacer.gif. etc.
Could the use of CSS sprites give a performance? Or give this other problems?
See http://spritegen.website-performance.org/section/what-are-css-sprites and http://www.alistapart.com/articles/sprites2/ for more information.
For best results, use the Firefox browser..