What with high pressure penalties, last minute corners, etc, now is a good time to consider the Yerkes-Dodson Law. This is illustrated in the figure to the left. Basically it shows how difficult you find doing a task, e.g., taking a good penalty, is as a function of how much stress you are under/how much adrenalin is in your bloodstream. The y-axis says learning but is known to be more general than just learning.
For simple tasks (solid curve), the more adrenalin, the better, i.e., the more likely it is that you complete the simple task correctly. But for tasks where you have to think (see the dashed curve), it is not so simple. A bit of stress, a bit of adrenalin, helps, but too much hinders you, and the chance of you failing goes back up. There is an optimal level of pressure where you perform your best. Being half asleep is bad, but so is being panicked.
I guess this is not so surprising. I guess most of us work best at most things when we feel some pressure, have some incentive, but not too much. But I found it interesting that not only is this called a Law in psychology but that it dates back to 1908, when Yerkes and Dodson did their original work.