In the June 19th edition of the Wall Street Journal, Melinda Beck quotes psychologist Stephen Josephson as saying, "Coaches and sports psychologists have always known that you don’t want your athlete to be relaxed right before an event. You need some ‘juice’ to go fast."
Beck quotes researcher Marianne Legato as saying, "There are people who subconsciously set life up to give them a thrill, by always being almost late, nearly missing a deadline, spending more than they should."
But HIGH anxiety can make even simple tasks more difficult–what you need is something in the middle. And that "sweet spot" is different for different people.