title: Colorbar slows down plot
body: <p>I am plotting many images in a loop on the same axes to make a video. Unfortunately the presence of a colorbar makes the loop a whole lot more slow. This happens even though I've "frozen" the colorbar using <code>caxis('manual')</code>.</p>
  
  <p>Why? I suppose there still may be listeners slowing the whole thing down, but it's really bad. Having frozen the colorbar there are no should be no calculations involved with it.</p>
  
  <p>Here's a demo that illustrates some of the workings of the colorbar, mainly with the aim of freezing it. There's no loop in the following.</p>
  
  <pre><code>close all
  figure(1);
  C = gallery('randcorr',10);
  ih = imagesc(1*C);
  ch = colorbar;
  % The colorbar disappears...
  ih = imagesc(2*C);
  % Must hold plot in order for it not to disappear
  hold on
  ch = colorbar;
  % Now, even though it doesn't disappear, it still changes!
  ih = imagesc(3*C);
  % Even if we use a lower lever function
  set(ih,'CData',4*C);
  % We must do this to freeze the colorbar
  caxis('manual')
  set(ih,'CData',5*C);
  ih = imagesc(6*C);
  % That worked!
  </code></pre>