cFolders Thumbnails strange behavior on calling an refreshing a site

I'm trying to use Thumbnails in cFolder Objects or Folders, but they behave strange when using IE6

When loading a site with Thumbnails, it seems that it lasts very long to load the Thumbs. For example, a site with 3Thumbnails shows them after 2Minutes. If i klick "Stop" or choose a link, the pics appear after earlier. What can i do to solve that?

This behavior can not be reproduced in FireFox!