You are reporting things indicative of serious problems that are unique to your system.
I partition the hard drives on machines I use and image/reimage the OS partition *all the time*.
If you have not messed with major things on your system yourself, then I can only assume that you blanket installed everything and anything Microsoft Windows Update offered you, optional updates and hardware updates and that some of them are responsible for your system slowing down to a crawl.
OS problems are a serious time waster. I have things setup on my desktop where I can reimage any of the four OS on my quadruple boot in 2-3 minutes - that's less time it takes to diagnose a major problem. Less time to make a couple of posts in your thread even
.
If my system as much as hick-ups, if my system shows delays of half a second, I nuke it in less time it takes me to go on a short bathroom break. By the time I come back it is already reimaged and rebooted into the state it was in when every single program, every single font was the way I liked it to be, when I made the drive image.