I have a user with a Dell XPS 13 9333, 8GB RAM, 512 GB SSD, running Windows 10 Pro x64. He is complaining of high CPU usage. It doesn't seem gigantic, around 25%, but he's noticing it. Rebooting makes no difference. It's in svchost.exe:

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I can kill all the processes listed under it with no effect, except for sihost; killing that logs out immediately. Webroot and MalwareBytes report no problems. (MalwareBytes I installed after the issue started.) Windows Defender is disabled. I tried clearing the event logs with no effect.