Weird FPS problem, anybody to help?

[HattoWW]

I have a weird problem, I'm playing the game with 4k resolution and had 45 fps, but nowadays my fsp dorps down to 20-25. If I press CTRL (or shift or ALT) button, then fps icreases 45 again but if I stop pressing CTRL then it drops down to 25 again.

 

I tried reinstalling game, reinstalling migoto, changed the d3dx.ini to the knight's version  etc. but nothing worked. Disabling mods with f2 or resetting mods with ctrl+alt+f10 didnt work. 

Now I'm trying to play the game with pressing CTRL button continuously.

 

Any solution for this?

[hlleloa]

If you are sure to play other games without this problem, you can disabed the most recently installed mod.