title: Are there any performance implications to including every header?
body: <p>Lets say I want to use <code>hex()</code> function. I know it is defined in <code>&lt;ios&gt;</code> header and I also know that it is included in <code>&lt;iostream&gt;</code> header. The difference is that in <code>&lt;iostream&gt;</code> are much more functions and other stuff I don't need.</p>
  
  <p>From a performance stand-point, should I care about including/defining less functions, classes etc. than more?</p>