In August 2010, I gave a talk at Cambridge Geek Nights on performance testing & instrumentation of web applications, and how having a good performance test framework helped us out at Texperts during three key moments in the history of our company:
I have put the slides on Slideshare: "Performance Testing and Instrumenting the KGB SMS Service for the Super Bowl"
My favourite slide: "Why Yes, Our System Architecture *was* a bit like Missile Command."