Unplayable fps after touching gamma

I played it now 100+ hours, my fps were all builds on high settings like 40-60fps (also 1.41). Now I touched the gamma slider and now my fps isn’t getting higher then 20 (on lowest settings).

I tried resetting graphics but it didn’t work. After that I reinstalled KCD and my GPU drivers but it didn’t help either. I checked everything now but it remains unplayable…

My specs:
Windows 10
I7 2600
12 gb ram
msi 1060 6gb
224 gb ssd
Coolermaster 1000w

Thanks in advance

That sounds like a really strange one!