Hearing Steve Souders at WordCamp last week got me thinking about website performance, so I went looking for more. The slides from his WordCamp talk are online, but he gave a similar talk at Google I/O which got videotaped and posted richer detail than his slides alone will ever reveal.
Also on his blog: Use the Google AJAX Libraries API when you don’t have a CDN, and a post that asks why make users wait to download all your javascript before they see the page if you’re only going to use 25% of it at first?