Yes with the new stuff in W10 all kinds of stuff going on in the background,usually when it is not supposed to.Latency base configuration is done now.
With respect to this thread my first questions was, can this Threadripper platform provide low latency in idle?
For me I got the answer: yes.
But I also wanted to know what causes the spike once the system is idle for some time.
Answer: Core parking as part of the power saving.
I used this exercise to get an idea of how the "Windows Performance Toolkit" works. Now I can say those tools eliminate the guesswork. LatencyMon tells you that you have an issue, but the tool kit gives you hints where and why.