How to size a vector properly?
<p>From <a href="http://stackoverflow.com/a/381756/179015">this answer</a>:</p>

<blockquote>
  <p>One place where you can run into a performance issue, is not sizing the vector correctly to begin with.</p>
</blockquote>

<p>So, how does one size a vector correctly when it is a property of a class? Is there a (best) way to set the <strong>capacity</strong> of vector (at initialisation)?</p>
