title: more efficient solution for QTableWidget write
body: <p>I am reading a PyTable, with 1320000rows x 16cols</p>
  
  <p>The idea is to read the table and to write its content into a QTableWidget.</p>
  
  <p>The way I am doing it makes the GUI collapse.</p>
  
  <p>I would like a clue about how to do it in an efficient way.</p>
  
  <p>Here it is my code:</p>
  
  <pre><code>#The PyTable is already opened and the reference to the desired table acquired
  
  self.ui.tableWidget.setRowCount(tab.nrows)
  self.ui.tableWidget.setColumnCount(len(tab.colnames))
  self.ui.tableWidget.setHorizontalHeaderLabels(tab.colnames)
  res = []
  
  #Read the PyTable row by row and store the result
  for x in tab.where('col1 &gt; -1'):
      res.append(x[:])
  
  #Try to write the QTableWidget row by row
  for i, row in enumerate(res):
      for j, col in enumerate(row):
          item = QTableWidgetItem(str(col))
          self.ui.tableWidget.setItem(i, j, item)   
  
  #NOTE 1: with a PyTable with 1000rows X 16cols rows aprox it works perfect
  #NOTE 2: with the huge PyTable with 1320000rows x 16cols, it does not work
  </code></pre>