I just got an early 2015 rMBP and the only that program that lags is Garageband, specifically when using the play/stop/rewind buttons, there is a 1-2 second delay when I press the button and it actually registering. Specs of my machine are 2.9ghz i5, 16gb ram, 512gb ssd. Is this just a glitch in Garageband? Or something wrong with my machine? Thanks for the help. edit: I forgot to add that I'm connecting it to an external monitor... could this be a potential cause reducing the performance?