Don't invalidate the options menu from the message list as we open a

message. We also invalidate it (twice) as we show the message. It turns
out to have measurable performance impact on 2.3 thanks to ABS

src/com/fsck/k9/activity/MessageList.java

@@ -1157,7 +1157,6 @@ public class MessageList extends K9FragmentActivity implements MessageListFragme
                 showMessageView();
             }
         }
-        invalidateOptionsMenu();
     }
 
     @Override