I havent experienced hibernating slower then usual startup.
Maybe mega new computers with fast CPU but still with HDD. Then faster maybe is usual startup then needed to read from swap file- hibernated information. Also if a lot ram hibernation is slower if its used all then all whats in ram is beeing written on hibernation and more is read from swap on start.
Hibernation is good couse u can stop working nothing is lost and start compter to immidiatly continue your work.
But if speed is mentioned then SSD are fast so using them will make hibernation also fast and theres another technology coming ive read about 3 weeks ago but cant find in google now - New Ram witch will hibernate in Ram. Yes with still all hardware off but somehow information stored like in USB Flash drives.
Also about hibernation in http://en.wikipedia.org/wiki/Hibernation_%28computing%29
After hibernating, the hardware is completely powered down (just like for a regular shutdown). Therefore a hibernated machine uses no more electrical power than one which is switched off -— modern machines, even if switched off, often consume a little power allowing them to be woken on an alarm timer, by Wake-on-LAN, etc. Hibernation thus allows to save electrical power, while avoiding the work associated with restoring all running programs after shutting down the computer, then switching it back on.
Hibernation is often used on laptops, which commonly have limited battery power available, and can usually be set to happen automatically on a low battery alarm. Most desktops also support hibernation, mainly as a general energy saving measure.
Hibernation is also useful if hardware maintenance must be performed which requires powering down the hardware (e.g. changing the CPU or the Power supply). For servers which need to be started up as quickly as possible after maintenance, hibernating and resuming can be quicker than shutting down, then restarting the server applications, and will allow long-running calculations to resume instead of being restarted.