title: Profit from noexcept with minimal effort
body: <p>I understand containers can optimize for types having noexcept move constructor / assignment / swap. But are there practical reasons (aside documentation) for specifying other operations as <code>noexcept</code>?</p>
  
  <p>Specifically, I'm interested if there are optimizations in the standard library to be gained by additionally having <code>noexcept</code>:</p>
  
  <ol>
  <li>Default constructor</li>
  <li>Copy constructor</li>
  <li>Copy assignment</li>
  </ol>