Originally Posted by Killswitch

Loading full size images takes up more bandwidth than a small image and then linking to full size, why you say that? Because the user only clicks on a couple pictures so out of those 4 they click in a gallery of 12, only 4 are using bandwidth, now if you use full size, then all 12 are being loaded.

Edit: Not to mention it makes your site seem like it's loading slow, thus making the visitor close your site before looking at it.