title: React Router avoid unmounting
body: <p>I have 3 routes that use the same component and based on the route display slightly different content. The problem is that on every route change the whole components mounts/unmounts from scratch leading to performance issues. What is the best way to avoid the unmounting but still use the same component and have these 3 routes?</p>
  
  <pre><code>&lt;Route path="/Products" exact render={Products} /&gt;
  &lt;Route path="/Products/shoes" exact component={Products} /&gt;
  &lt;Route path="/Products/books" exact component={Products} /&gt;
  </code></pre>
  
  <p>React Router version 4.</p>