A 10 Gb change in free space is relatively small and can appen within a day or two, both up and down.
As long as your free space don't consistently drop under 15 Gb, you have nothing to wory about.
Some causes include:
Change in the content of your temporary internet files. It can sweel and shrink by very large amount in a short time.
Installation and updates of the operating system and applications.
You got the installation files to upgrade to Windows 10.
Accumulation of restoration points.
If you enabled the Hybernation feature, it will take as much space on your primary drive as you have RAM installed. It can easily amount for 8 Gb or more on a 64 bits system.
LOT of stuff in the recicle bin. (think to empty it periodicaly)
If you use internet explorer, set the maximum size for the temporary internet files to a lower value. About 10 to 50 Mb are normaly enough.
Install Firefox. It allow you to set the size of your internet cache.
Chrome DON'T allow you to limit the size of the internet cache/temporary internet files and it can grow to fill all of your drive!
Periodicaly run Ccleaner to purge left over files.
I don't see the point in using that Disconnect addon. It only track and manage cookies. Cookies can't "run" as they are PURE TEXT snippets. Granted that they are almost never human readable, but they are still ONLY text.
AddBlock Plus exist for Firefox, Internet explorer, Opera, Chrome and Safari. "take controll" seems to imply that it only work on Chrome, while it was originaly only available for Firefox.
Never turn off system restore. You want to just limit the number of restoration points. No need to keep over a month worth of restoration points, or about 10 or so.
If you have an SSD, you must NEVER defragment it !
Defragmenting an SSD can damage it, shorten it life and cause it to loose some of it's capacity.
You only defragment conventional hard drives.
Electro, November 2015
