While I have not used the command line hibernate, I have used the standard shut down/hibernate procedure (going into settings and activating from there; not a restart) several times recently when I was conducting the battery tests I've done in another thread. I had task manager open for other reasons (tested why I was getting better battery life with Balanced as opposed to Power Saver), I noticed no out-of-ordinary CPU usage. As for hibernate and Sleep, I use these extensively and again when I was testing battery life, and would also have noticed any battery life/excessive CPU utilization.
Here is a video of my Surface Pro 2 with microSD card inserted, going into and coming out of hibernate (sorry for the crappy quality). As you can see, it hovers around 4-6% CPU utilization for about a minute after coming out of hibernate, then falls between 1-2% as normal.
[video=youtube_share;vbJ-8S6jAu8]http://youtu.be/vbJ-8S6jAu8[/video]
