Just to document what I've said above in case it helps anyone.
This behaviour is what I'm referring to - https://www.reddit.com/r/oculus/comments/hwii1s/oculus_program_100_cpu_usage_bug_for_windows/
For me, I noticed that after installing Oculus, my computer fans were nearly always running at high/max, and my GPU was being throttled due to thermal issues (this in a laptop). I tried an eGPU (1060 6gb) and got not much better FPS due to thermal throttling of the CPUs than with the internal (Quadro T2000), which made me suspicious, especially when my non-VR performance took a massive hit. So I did some digging.
With the internal GPU, I'll get 38-40fps in VR for about 15 seconds, then boom, it drops to 7/8, and stays there for a couple of minutes, then I got 15 seconds of 38-40, repeat. Using GPU-Z and logging, I could correlate those times with thermal throttling. I spent ages trying to find the cause, and after a lot of frustration, including uninstalling nearly everything, I started using the Dell Power Manager application to try to tweak when fans came on etc. It kept complaining that I was using a High Performance power plan, so I kept setting Balanced then finding that something switched it. Lots more digging and experimenting, and it became obvious that it was related to putting the headset on and off.
At that point I had a useful Google search term - "Oculus sets high performance power plan", which lead me to a number of threads where it was documented that, in a move to ensure low-latency in VR, Oculus was disabling the idle state of the CPU, which meant that, for systems where cooling is an issue, e.g. laptops, the CPU would overheat and start to throttle itself.
So now, if I'm going to fly, I launch a batch file which sets the power plan to balanced every 60 seconds (I tried continously re-enabling the idle state with PowerCfg /SETACVALUEINDEX SCHEME_CURRENT SUB_PROCESSOR IDLEDISABLE 000 too, but just setting balanced did the job). It could be smarter, but it does the job.
I now get 40fps stable and consistent in VR on my internal GPU, which is well below minimum VR spec.
If anyone is interested (though it seems that sharing VR settings is largely pointless 'cos everyone's setup is different), here's what I'm using for Oculus Quest on a Quadro T2000 4GB based laptop:
OTT Quest Link - Distortion = Default, Encode Res = 2016, Bitrate = 200
OTT Game Settings - SS 1.0, ASW = Off, Adaptive GPU scaling = On
Oculus Settings - I set the resolution to the lowest
DCS - Textures High, Terrain Low, everything else on minimum or off, except: Cockpit Displays = 1024, Anisotropic = 2x. PD = 1.0, Hotplug Off.
and, of course, I run my batch file to constantly set the power plan back to Balanced.
It's definitely not ideal, but flight is pretty smooth, and displays are readable (I'm mostly in the A10C-II), the HUD is readable except with a very bright background (e.g. white cloud).
