title: Unit test execution speed (how many tests per second?)
body: <p>What kind of execution rate do you aim for with your unit tests (# test per second)? How long is too long for an individual unit test? </p>
  
  <p>I'd be interested in knowing if people have any specific thresholds for determining whether their tests are too slow, or is it just when the friction of a long running test suite gets the better of you? </p>
  
  <p>Finally, when you do decide the tests need to run faster, what techniques do you use to speed up your tests?</p>
  
  <p><em>Note: integration tests are obviously a different matter again. We are strictly talking unit tests that need to be run as frequently as possible.</em></p>
  
  <hr>
  
  <p><strong>Response roundup:</strong> Thanks for the great responses so far. Most advice seems to be don't worry about the speed -- concentrate on quality and just selectively run them if they are too slow. Answers with specific numbers have included aiming for &lt;10ms up to 0.5 and 1 second per test, or just keeping the entire suite of commonly run tests under 10 seconds. </p>
  
  <p>Not sure whether it's right to mark one as an "accepted answer" when they're all helpful :)</p>