Yahoo and their development team in particular deserve kudos much more often than they seem to get. PR-wise, they get elbowed out by Google, FB, etc. when in fact their open-source tools like YUI are often very well made, well tested (if it's good enough for the Yahoo front page, it's probably pretty good), and most importantly for fellow developers, well documented. Thanks Yahoo!
Oh, and I forgot to mention YSlow - as far as I can tell, that Firefox plugin was available years before anything else like it (e.g. Chrome's performance profiler). Not only did it work and work well, but the Yahoo! devs released lots of documentation and videos around how to improve site performance, i.e. free education from people who dealt with massive scale daily.
Completely agree. Personally, I've been using the javascript testing framework from YUI 3 and it's been great so far. It's pretty easy to setup and I can even have the test output as a JUnit xml file. Did someone say Hudson integration?
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.
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.
