Traversing the entire DOM on page load and rewriting all links for large pages would also slow down the page though.

Also rewriting links seems too intrusive for my tastes and means I cant "Copy link location" which I frequently do. I like the idea, but I personally would have just used a single "click" event handler on the entire page using the capturing phase and hijack links to redirect through your site first, rather than doing a rewrite for every link in the dom