You can have it down to ~20sec (excluding BIOS time).
-> Make sure your SATA controller is set to AHCI mode
-> Deep defrag your HDD with something like O&O Defrag, (pick Optimize/Complete), this mode will put the most used files and boot process at the begging of your HDD where it's faster to access it, and the rest will follow. The process is very time consuming... you may want to leave it over night as you sleep (don't forget to turn off sleep before doing it, and turn back sleep after)
I had 19sec with my HDD with the above,
For instant boot you need:
-> Fast SSD
-> FULLY supported UEFI motherboard
-> GOP supported GPU (you need to contact the graphic card manufcature to get the firmware to make it GOP ready. Because, once it's GOP ready, it will no longer function on a traditional BIOS. Also not all GPU are ready for this, and it varies between manufactures to manufacture, depending if they put a firmware chip with sufficient space to support this updated firmware. EVGA GTX 600 are ready, that I know.
-> CSM turned off
-> SATA Mode set to AHCI
-> FastBoot enabled
-> Windows 8
If you have the above, your system will boot like this:
HP/Microsoft: http://www.youtube.com/watch?v=P_QIi8xQ9Fg
ASUS:
ASRock:
"-> FastBoot enabled"
Is this something in the BIOS or in the OS?