This is good advice, but not optimal. Using multiple domains in this case will actually slow down the site because of the additional DNS lookups -- only do tha

This is good advice, but not optimal. Using multiple domains in this case will actually slow down the site because of the additional DNS lookups -- only do that if you are serving up a ton of images. a) The CSS file should be inline. b) The images should be done away with entirely by including them as a data uri. c) For IE6-7 (data uris not supported) the fallback image should be sprited. d) For bonus points (if you want HN to be served nearly instantly, globally) splurge for an application caching CDN provider like Akamai.