I would say option 2 (proxy with cache), where you only download requested images and try to cache them for a reasonable period of time that allows most users to see the post on the front page without much problems, and delete it afterwards (I’m not sure what value this would translate to, I’ve seen mentions of 48hours but that might be either too much or too little, I guess you know best what would work). I mostly use Lenny to browse new content, so that is most important to me. If I would ever go and explore older posts, I won’t mind older images possibly being broken.