ntoskrnl.exe!_misaligned_access eats a lot of CPU when idle

The CPU usage is by design. It comes from the function ntoskrnl.exe!RtlScrubMemory / ntoskrnl.exe!RtlpGenericRandomPatternWorker / ntoskrnl.exe!RtlpTestMemoryRandomUp.

This function write random patterns to the RAM to test the RAM for errors. Windows does this during the Idle Maintenance task to optimize Windows (cleanup of WinSxS, optimizing .net files with ngen)

Run the Task Scheduler, go to Microsoft -> Windows -> Task Scheduler, select Idle Maintenance,

do a right click and select disable.

Unfortunately I didn't have this setting in Task scheduler so I didn't have anything to disable. (I'm on Windows 10 b1607)

But what actually helped is adding a DWORD value MaintenanceDisabled with value 1 to this key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\Maintenance

After this my idle CPU usage stopped being high.

You can see more details here: https://www.tenforums.com/tutorials/40119-enable-disable-automatic-maintenance-windows-10-a.html