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.
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.
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