Microstutter relating to on-demand CPU frequency and use of multiple cores.

[Frawg]

So sometime in November 2017* I started getting microstutter in Warframe and seemingly only Warframe. (microstutter being where a frame takes much longer than average to render, but otherwise is able to achieve rendering approximately 60 frames over a second's time. See https://imgur.com/WQdAs07.)
* November 19'th is of a screenshot I took. I lived with it for maybe a week, so no later than 22.3.4 (nov 16; as 22.3.4 is on Nov 20), and I bet no earlier than 22.2.5 (Nov 11)

I eventually deduced it was related to the frequency governor. Leaving at windows default to where it downclocks to power save ("Balanced" in the power options menu) causes warframe to render frames much longer than average; but changing the governor to where it keeps the CPU frequency at max all the time fixes it ("High Performance").

If I run warframe on a windows in a hypervisor (libvirt+QEMU+KVM+exact same hardware as bare-metal) the microstutter does not appear, despite linux's frequency governor is cpufreq-ondemand. (I however get a noticeable performance drop relating to CPU in Cetus in this VM (GPU has 20-40% usage yet only getting 40 fps))

I've also noticed that pinning the game to 2 cores (via Set Affinity in the right-click menu of the Details tab in Task Manager) soothes it (possibly stopping it). Giving it access to 3 or 4 cores causes microstutter (tested only on the bare-metal install).

I have verified the game cache and even reinstalled the game fresh; I have reinstalled windows; reinstalled the graphics drivers prior. Warframe graphic settings were set to the lowest possible (all low or if possible off) **; NVIDIA pre-rendered frame setting both at application-setting and at 1; defaults for everything else in the NVIDIA Control Panel; disabling SweetFX. None of these helped. Only the CPU frequency governor and CPU pinning helped.
** Even if I restart the game and verified the game cache after setting the settings to low, it still seems that the graphic qualities are set to high.

My setup is as follows:
Windows 10 version 1709 (Build 16299.192)
Intel Skylake 6600k @ 4.5GHz ***
NVIDIA GTX 960 (driver 388.13) ***
*** Overclocks for both have been the same as it were for 2 years; microstutter issue is recent to the last 2 months, so I doubt this is related.