title: Plotting large arrays in pyqtgraph
body: <p>For an electrophysiology data analysis set I need to plot a large 2D array (dim approx 20.000 x 120) of points. I used to embed a Matplotlib widget in my PyQt application, but went looking for other solutions because the plotting took quite long. Still, plotting the data with pyqtgraph also takes much longer then expected, probably because it redraws the widget everytime when using the plot() function. </p>
  
  <p><strong>What is the best practice to plot large arrays?</strong> </p>
  
  <p>The pyqtgraph examples, although extensive, didn't help me much further...</p>
  
  <pre><code>import pyqtgraph as pg
  view = pg.GraphicsLayoutWidget()
  w1 = view.addPlot()
  
  for n in data:
      w1.plot(n)
  </code></pre>
  
  <p>or</p>
  
  <pre><code>w1.plot(data)
  </code></pre>
  
  <p>The last rule generates <em>ValueError: operands could not be broadcast together with shapes (10) (10,120)</em> </p>
  
  <p>Thanks in advance....</p>