Hello I was working on this all day and did a variety of things (i.e disabling windows search, superfetch, reseting virtual memory, clearing temp files, turning off notifications, disabling firewall windows defender etc).
This is what worked instantly
Go to your windows search bar and type cmd, when it pops up right click it and run as admin, type "WPR -cancel" and that should do the trick and lower System disk usage.
This problem started happening after the knew windows 10 update for a lot of people so if your effected by this i hope this short guide helps you out.
(you might have to do this every time you turn on your computer until they fix this)
Edit: just a heads up. For more in depth explanation about what the command your turning off does: wpr calls the Windows Performance Recorder. It is a performance recording tool that records system events to your disk which you can analyze. "-cancel" will cancel the current recording without saving the recorded data. In this case this fixes the problem. Make sure if anyone like me is is giving you advice like this to go into command promote that you google what the command does first to avoid risk to your PC!! ESPECIALLY if someone says to run it as admin. *credit to /u/Zahand for the information about what the command does
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Post was last edited on December 12, 2016 12:02 AM PST