This thing really grinds my gears. I reinstalled Windows twice today. I tried it with and without my Wi-Fi adapter, and different driver versions. I've tried turning off Wake On Lan. New USB drivers, new ethernet drivers. Went back to a previous bios version. I was expecting it to be a driver issue, but upon a fresh Windows 10 installation the CPU usage was over 50% on the first thread upon the initial boot without anything installed.
The problem is that Interrupts due to ACPI.sys is causing core 0 (thread 0) to run at around 50% usage.
LatencyMon showing a I high ISR count for ACPI.sys and high total execution time. You can see that I only ran it for 2 minutes and 4 seconds, which resulted in an ISR count of over 16 million, with a total execution time of 79 seconds out of that 2 minutes and 4 seconds that I ran LatencyMon.
And a Windows Performance Analyzer recording:
The thing is, that sometimes putting it to sleep and waking it up, or rebooting will temporarily fix it so that CPU usage can drop to 0%. This never lasts more than a few minutes. I do not know if it had this problem before the Windows 10 Creator's update. I didn't notice it initially but I may have just not been paying attention. I'm not sure if I want to download yet another ISO to try out.