Go to http://forums.fark.com/cgi/fark/comments.pl?IDLink=2010733 and scroll the page after it loads the images (all the way down). Safari will spike to just over 400megs of memory being used. If you close the tab and then wait, only about half of that amount will be released. However, this could just be a bug in ImageIO.
The test site is no longer usable (images have all been removed). We do not know of active memory leaks -- please reopen with a modern test case if you believe this is still a concern.