Since I got the new 15in MacBook Pro with retina display I have been wondering why it took so long to restart after sleep. Sometimes it was quick, other times frustratingly long. It seems the problem lies with the new standby facility which is set to come into operation after one hour of sleep. Everything in memory is written to disk in order to save standby power. So if you restart after more than one hour everything has to be moved back into memory.
I was happy to see this useful tip for amending the time before the hibernation kicks in. The suggestion here is 24 hours, although you can choose your own duration. It does involve a simple terminal command but it is straightforward and effective.
by Mike Evans, 26 March 2013