Yeah, lots of people with very expensive cpu and gpu are complaining about the same, for me with a mediocre pc, my biggest issue are the amd drivers, I had to roll back to October version. Those after that only cause me CTD.
I can fly with A320 nx only between 45 an 60 at medium settings and 25 to 35 I think with high settings. All situations are caused by main thread limitation. Also, my ram goes to 10 or 12 gigs on Sim usage and my gpu only goes to 4 or 5 max and in both case those fps are alway jumping like crazy.
My specs are:
Amd ryzen 7 3800x oc to 4.5 all cores;
Noctua d15h dual fan 140mm;
Sapphire nitro Rx 5700xt 8gb oc edition;
X470 gaming plus max;
Gskill trident z rgb Amd edition cl16 3200mhz 2x8gb;
2 ssd 500gb and 2 hdd, one with 1.5tb and 1 with 1tb.
Not the top machine but can do some flights, even with not much fps.