title: QTextEdit.insertHtml() is very slow
body: <p>I've given up on actually trying to make it go faster. </p>
  
  <p>My biggest problem is that when I'm inserting the html, the application slows down to a crawl.
  I have a progressbar, and I'm calling </p>
  
  <pre><code>QCoreApplication.processEvents()
  </code></pre>
  
  <p>(I'm using pyqt, by the way)</p>
  
  <p>Can I put insertHtml() into a different thread, so I don't have an unresponsive interface?
  How would I go about that? I've looked into QThread and QThreadPool, and I'm not quite sure where to begin.</p>