How to Ajaxify a Drupal 7 Views block
You might try the Lazy Image Loader.  I'm not sure if it will work for your case, but it's worth a shot.  You can also implement the lazy behavior yourself.  Use javascript to test the "complete" property of each image, and change the src attribute on any image that currently hidden from view.  When it becomes visible, swap in the original src.  I've seen good results with this script: http://www.appelsiini.net/projects/lazyload.