My relatively new Early 2015 rMBP is taking close to 35 seconds from the point I press the power button to when the Apple logo appears on the screen. From the Apple logo to to the login screen is about 5 seconds, during which there is the progress bar. Even a warm reboot takes the same 35 seconds from "bong sound" to the Apple logo appearing on screen. What is the Macbook Pro doing during those 35 seconds of completely blank screen? The backlight is on, but that is it. Is this normal? Anything I can do to speed that up?