Josh Emerson, from:
(Responsive Enhance) A technique where a small image is always downloaded. If needed, a large image is downloaded in the background, and replaces the small image only once it’s fully downloaded. This results in a faster perceived page load speed, but a slower actual speed. I’m happy with this solution as I care more about perceived speed than actual speed.
I like the idea of this, although I’ve yet to use it. Download Responsive Enhance from GitHub (whatever that is).