Latency is the mother of interactivity

HighScaleability.com on latency and how to crush it:

The less interactive a site becomes the more likely users are to click away and do something else. Latency is the mother of interactivity.

and

Amazon found every 100ms of latency cost them 1% in sales. Google found an extra .5 seconds in search page generation timedropped traffic by 20%. A broker could lose $4 million in revenues per millisecond if their electronic trading platform is 5 milliseconds behind the competition.

and then about 1,000 easily read words on how to decrease latency. Well worth the time.