Some amounts of stress are good to push you to the next level of optimal alertness, behavioral and incredible performance. But it's a slippery slope on which you can tumble quickly.
This image is a wonderful expression of how stress can soar our performance. The problem is in the length of time we stay in each segment. No stress leaves you complacent and probably bored especially if you are a top performer, but too much is probably causing you to loose focus, have anxiety, sleepless night... not at all helpful in being productive or creative.
Take note of where you are most consistently in your day to day. Are you using stress to your advantage, in a healthy way or not?