Wake Up Your Mac Faster: "You can change the Macโ€™s hibernate behavior using pmset; hereโ€™s the reference for it:

http://developer.apple.com/documentation/Darwin/Reference/ManPages/man1/pmset.1.html

โ€œsudo pmset -a hibernatemode 0โ€ณ = suspend to RAM only (default on desktops)
โ€œsudo pmset -a hibernatemode 1โ€ณ = suspend to disk only
โ€œsudo pmset -a hibernatemode 3โ€ณ = suspend to disk RAM (default on laptops)"