of the compiler, the tier mechanism may have a small performance penalty compared to using
non-const reference parameters as a mechanism for returning multiple values from a function. 
For example, suppose that the following functions <code>f1</code> and <code>f2</code> have equivalent functionalities:

<pre><code>void f1(int&amp;, double&amp;);
tuple&lt;int, double&gt; f2();
</code></pre>

Then, the call #1 may be slightly faster than #2 in the code below:

<pre><code>int i; double d;
  ...
f1(i,d);       