Since P3D v4 I had always this problem and I never fixed maybe it's normal or maybe I do something wrong .
When I have OpenLC installed I lose almost 25-30 fps or more, to give you an average my framerate is between 17-25 fps on the simulator and when I desactivate OpenLC I have a smooth simulator with almost 60 fps constantly.
I have uninstall and install several times already, as well trying to tweak the Prepar3d.cfg but without success.
My system is a 8700k OC 4.8 Ghz, 16 Gb, 2080 Ti
Thanks in advance.