I also started getting low FPS problem and I have never had it before even in BETA testing. Few days ago I made a successful flight from LJLJ to EDDF. Yesterday I powered on my PC, turnet off Hyperthreading to test this:
After turning it off I started P3D with CRJ and had 30+ FPS in cold and dark. As soon as I turned the AC power on and avionics came to life my FPS dropped to 15 or less FPS. I thought that HT set to off in BIOS is causing this problem. After a restart and turning the HT back on the problem was still there. I am 90% sure that turning HT off and back on has nothing to do with FPS problem. But it is interesting that this is the only change on my system between a smooth CRJ experience and low FPS problem.
I deleted the P3D cfg file, reinstalled the CRJ and there was no change.
Then I started searching for the problem. I tried FSLabs and PMDG NGXu and had 25+ FPS. CRJ is still having 15FPS on AC power and 30+ without AC.
Then I turned all the settings to the left (LOW) in the P3D and still had exactly the same amount of FPS while on AC power. So P3D settings had no impact.
The only improvement was switching off the FO displays - FPS jumped to 20 but it is still quite low and if I also turn the CPT screen - FPS jumps to 30.
Was there maybe a Windows 10 update I don't know about it and started this problem?
I doubt my PC is underpowered for CRJ:
Windows 10 1903 18362.535
i7-7700 (4.2 GHz, HT enabled)
16GB DDR4 RAM
Gigabyte RTX 2070 Super Gaming OC
I am so confused about this problem