Stephen O'Grady - Speed is a Feature:

"A big part of the equation that is Google is speed, pure and simple. Very low latency performance, delivered from their secret sauce architecture. [...] The interesting thing is that speed is not traditionally considered a feature, per se. It's a design consideration, to be sure, but in the applications I've developed speed has rarely been a part of the requirements gathering phase - apart from occasionally defining what consitutes unacceptable performance (greater than 8 second load times on web pages, for example).

[...] What's the catch in all of this? Speed is [much] easier said than done, and depending on the application type might be near impossible for smaller players to deliver on cost constrained hardware platforms."