Schedule Time Bug?

I have a fairly simple 'state' machine for moving between different guis within my system, splash screens, attract screens etc. I have just moved the code across to my new dev machine and the timings are massively different. The code I am using is:

function nextGUI(%transitionEvent)
{
   %currentGUI = Canvas.getContent() ;
       switch$ (%currentGUI.internalName)
      {
         case "splashScreenGui":
            Canvas.setContent(mainMenuGui) ;
            //Stay on the Main Menu for 8 seconds unless an option is selected         
            $GuiSchedule = schedule(8000,0,"nextGUI","Time") ;
            
         case "mainMenuGui":
            if (%transitionEvent $="Time")
            {
               Canvas.setContent(highScoreGui);
               $GuiSchedule = schedule(8000,0,"nextGUI","Time") ;
            }
            else if (%transitionEvent $="StartGame")
            {            
               Canvas.setContent(gameGui) ;
               $GameStarted = true ;
            }
            else if (%transitionEvent $="Options")
            {
               Canvas.setContent(optionsGui) ;
            }
         
         case "highScoreGui":
            Canvas.setContent(mainMenuGUI) ;
            $GuiSchedule = schedule(8000,0,"nextGUI","Time") ;
     }

On my laptop the timings seem about right, i.e. approx 8 seconds to flip between the mainMenu and the HighScore table. On the new box this is about 0.5 seconds, if that. The new dev box is pretty high spec. Any ideas?