Well, I notice this a while back, at first I thought that's because my internet bandwidth was poor.
When I open a page with pictures, it usually loads very slowly.
Soon I figured out that the small previews are not thumbnails, they are full sized pictures that got resized!
So if I open a page like this:
http://www.chronocompendium.com/Term/Official_Art_(Chrono_Cross).htmlMy browser has to download ??mb of data (I don't know how many exactly, but after I took a shower, it was still being downloaded)
Edit*
61.2 MB (64,263,055 bytes)