Ugh, yeah Apple mobile sync is another bad one. Basically it keeps a copy of all the files on your iPods, iPhones, and iPads (music, photos, videos, etc) on your C drive. I hear there's an option to change this behavior, but others will have to fill you in. I don't use it, I've only run across it a few times while cleaning up other people's computers.
The hibernate file is only necessary if:
- You need to hibernate your laptop (i.e. keep it off for days or weeks at a time without draining battery, but need it to restart quickly).
- You use Windows Fast Startup on your desktop. This allows Windows on a HDD to boot up in roughly half the time it would take from a cold boot.
In particular, if you have a SSD, the hibernate file really does nothing for you. A cold boot from a SSD is nearly fast as waking from hibernate. I just disable hibernate on SSD systems.
http://www.sevenforums.com/tutorials/819-hibernate-enable-disable.html
If you have lots of free RAM (e.g. you have 8 GB and rarely use more than 4GB, or you have 16GB and rarely use more than 8-10 GB), then you can reduce the default pagefile size. This was a bad thing to do on a HDD because the pagefile is quickest when it's one contiguous file. But that doesn't matter on a SSD. Go to the pagefile settings (This PC -> right click -> properties -> Advanced system settings -> Performance Settings -> Advanced -> Virtual memory -> Change). Change to a custom pagefile with an initial size around 512 MB - 1 GB, and a max size of the amount of RAM you have. If you want, you can even play with moving the pagefile to your HDD (which will be really slow if you use up all your RAM, but not that big a deal if that never happens).
Edit: I should also add, to maintain maximum write speed on a SSD, you should try to keep about 15%-25% of its space free.