title: Python slow execution
body: <p>I made a script which inserts two lists into another every each 4 element but it takes a really long time to complete.
  Here are my two very long lists:</p>
  <pre><code>listOfX = ['567','765','456','457','546'....] len(383656)
  listOfY = ['564','345','253','234','123'....] len(383656)
  </code></pre>
  <p>And the other list which contain some data and where I want to add the data of the other lists:</p>
  <pre><code>cleanData = ['2020-04-28T01:44:59.392043', 'c57', '0', '2020-04-28T01:44:59.392043', 'c57', '1'....] len(1145146)
  </code></pre>
  <p>Here what I want:</p>
  <pre><code>cleanData = ['2020-04-28T01:44:59.392043', 'c57', '0', 567, 564, '2020-04-28T01:44:59.392043', 'c57', '1', 765, 345]
  </code></pre>
  <p>Finally, here my code:</p>
  <pre class="lang-py prettyprint-override"><code>  ## ADDING X AND Y TO ORIGINAL LIST
    addingValue = True
    valueItem = &quot;&quot;
    loopValue = 3
    xIndex = 0
    yIndex = 0
    print(len(listOfX))
  
    while addingValue:
  
      if xIndex &gt; len(listOfX):
        break
  
      try:
        cleanData.insert(loopValue, listOfY[yIndex])
        cleanData.insert(loopValue, listOfX[xIndex])
  
      except IndexError:
        addingValue = False
        break
  
      xIndex += 1
      yIndex += 1
      loopValue += 5
  
  </code></pre>
  <p>Do you have any idea?</p>