title: When should I use `withMutations` on a map in Immutable.js?
body: <p>I have a series of mutations to make on my Immutable.js map. </p>
  
  <p>At what point should I prefer using <code>withMutations</code> rather than creating intermediate immutable maps?</p>
  
  <p>From the Immutable.js docs:</p>
  
  <blockquote>
    <p>If you need to apply a series of mutations to produce a new immutable
    Map, withMutations() creates a temporary mutable copy of the Map which
    can apply mutations in a highly performant manner. In fact, this is
    exactly how complex mutations like merge are done.</p>
  </blockquote>
  
  <p>But, where is the line? If I need to make two mutations should I use <code>withMutations</code>?</p>