title: Will using a parallel stream on a single-core processor be slower than using a sequential stream?
body: <p>I am applying an operation to every element in a very large <code>LinkedList&lt;LinkedList&lt;Double&gt;&gt;</code>:</p>
  
  <pre><code>list.stream().map(l -&gt; l.stream().filter(d -&gt; 
  (Collections.max(l) - d) &lt; 5)
  .collect(Collectors.toCollection(LinkedList::new))).collect(Collectors.toCollection(LinkedList::new));
  </code></pre>
  
  <p>On my computer (quad-core), parallel streams seem to be faster than using sequential streams:</p>
  
  <pre><code>list.parallelStream().map(l -&gt; l.parallelStream().filter(d -&gt; 
  (Collections.max(l) - d) &lt; 5)
  .collect(Collectors.toCollection(LinkedList::new))).collect(Collectors.toCollection(LinkedList::new));
  </code></pre>
  
  <p>However, not every computer is going to be multi-core. My question is, will using parallel streams on a single-processor computer be noticeably slower than using sequential streams?</p>