title: what does --enable-optimizations do while compiling python?
body: <p>I'm trying to compile Python 3.6 on an arm based Linux machine, 
  <code>./configure</code> outputs this:</p>
  
  <blockquote>
    <p>If you want a release build with all optimizations active (LTO, PGO, etc),
    please run <code>./configure --enable-optimizations</code>.</p>
  </blockquote>
  
  <p>what does <code>--enable-optimizations</code> do?</p>