title: How can I make this Tkinter app run faster
body: <p>I've written a simple Conway's Game of Life in Python Tk, but it is so utterly slow!<br>
  On my PC it ran somewhat fine, but on my school computers it couldn't reach 10 refreshes a second. I suspect the drawing part lags a lot, how can I fix that?
  </p>
  
  <pre class="lang-python prettyprint-override"><code>def drawCells(self):
      self.board.delete(tk.ALL)
      for i in range(self.gridsize):
          for j in range(self.gridsize):
              if self.cnow[j][i] == 1: # cells now list
                  rect = self.board.create_rectangle(
                      i * self.grid,
                      j * self.grid,
                      (i + 1) * self.grid,
                      (j + 1) * self.grid,
                      fill="#000000")
  </code></pre>
  
  <p>I don't know if pasting the entire class is necessary, but if needed I'll append the rest of the code.</p>