<span class="identifier">number</span></code> takes
      a second template argument, which, when set to <code class="computeroutput"><span class="identifier">et_off</span></code>
      disables all the expression template machinery. The result is much faster to
      compile, but slower at runtime.
    </p>
<p>
      We'll conclude this section by providing some more performance comparisons
      between these three libraries, again, all are using <a href="http://www.mpfr.org" target="_top">MPFR</a>
      