Steve "High Performance" Souders jumped ship and went to Google though.

sh1mmer · on June 25, 2010

Steve definitely kicked "high performance" into overdrive at Y!, but he's one of many people who have contributed from Yahoo:

Stoyan Stefanov write weekly about performance on his blog http://www.phpied.com/ and actually just released "Web Testing Framework" at Velocity which is a YSlow plugin.

Nicholas Zakas wrote "High Performance JavaScript" (http://www.amazon.com/Performance-JavaScript-Faster-Applicat...) and does a ton of stuff for the Yahoo frontpage.

Phil Tellis (author of Boomerang) regularly blogs on performance on http://bluesmoon.info

I (sh1mmer) have done a bunch of performance related stuff with Aristus (now at FB) and I'm working on how network, consumer hardware and other holistic factors affect web performance. Expect some DNS related stuff soon.