When I turn my laptop on after it hibernated and even when I’m at the point where I’m at my desktop and I can… well, use my computer… there is still a lot of (constant) disk writing going on for about 3 minutes. I’m using Windows 7 if that helps. But what else could the hard drive be loading?
Hibernation means that all of the that was in RAM gets stored on the hard drive. If you have hibernation enabled, there is a file (hiberfil.sys) that exists in the root of the drive. After the computer boots up, it has to clear this file so that the next hibernation will work properly.
Additionally, even though some of the information in the file has been loaded, the rest of it needs to make its way into RAM.
It needs to reload the RAM with the data stored on the disk before hibernating. This means a few GB.