The good news is that it works (the images are now loading all the way through a thread), Gil. Nicely done and thanks because it really is awesome.
The bad news is that a friend just linked a 2818x4062 image to me and I clicked it once to make it native size, then once to make it small again, then again because I thought the click hadn't registered (where actually it was just slowly trying to render it) and then my PC crashed.
I'm thinking maybe you should set a max size, or switch off that feature if it's no longer needed (as I understand it, it's only there as a workaround for images not loading?).
I have a quad-core i5, a GTX 470, Windows 7 Pro SP1 and the latest Chrome, by the by.