Over the weekend I upgrade to win 8.1 and after upgrade I found my disk usage at 100% and it was getting super slow, plus I only had couple of Gig left on it.

The solution I found was to do a disk cleanup, using the cleanupmgr.exe

Here are the steps:
1. Use windows key + Q
2. Search for cleanup
3. Launch the cleanup manager


A window should launch for disk clean up click on the “clean up system files” button, the application will relaunch and will add more options, it may take some time at this point for it to relaunch.

Click on “Previous Windows installation(s)” and “Windows Update Cleanup” , and do a cleanup of the files. This fixed the issue of my drive hitting 100%.

There is also another note on microsoft community about this where 2 different steps are given. I personally havent tried those since disk cleanup worked for me, but here is the link for it: