Thanks for the quick response. Some of my users were asking about it because they are having some issues with the page "jumping" they are computer novices though and I suspect it is just the typical page load shuffling that happens as images are loaded. Our threads tend to have several images per page in addition to the ones in signatures. 10 to 15 images in a single page isn't uncommon.
I'm using the image proxy to help with baseline performance and it does make a difference.