Hezban you say the game works fine for a couple of sessions. Do you mean after two sessions the game never goes back to 140fps unless you reinstall the game? Or do you mean if you turn the computer off and let the CPU cool down for a while the game goes back to 140fps?
The yellow CPU line in the graph is spiking really bad. I notice you have a 6 core/12 thread CPU but the game thinks you have a 16 core processor.
Are you using a custom user.cfg file?
I can't tell if Job Threads is 8 or 0 in the screenshot. Please let me know what the number is.