For some reason is affecting all those using "Prefer AC-3" option and disabling that option improve the zapping time and it seems the cause is that MP is reconfiguring and pausing/restarting the graph on client side twice

h4. Steps to Reproduce
Test some SD and HD channels zapping with "Prefer AC-3 sound" enabled/disabled and see the zapping time

h4. Additional Information
Logs and details here:

http://forum.team-mediaportal.com/549725-post76.html

http://forum.team-mediaportal.com/549756-post78.html