Index: action_details.html
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--- action_details.html	(revision 20686)
+++ action_details.html	(revision 20687)
@@ -206,6 +206,10 @@
 </table>
  
 
+<h3 id="benchmark">benchmark</h3>
+<p>
+This action is used to speed-test the GUI rendering.  It redraws the current screen as many times as possible in ten seconds. It reports the amount of time needed to draw the screen once, in average. 
+
 <h3 id="boardflip">boardflip</h3>
 <p>
 All objects on the board are up-down flipped (mirrored over the x axis).