How to Solve?

OK. Solved here!

Lostark.exe

  • 1) Disable full screen optimization.
  • 2) High DPI override fix.
  • 3) Run as administrator.

Nvidia Control Panel:

Note: I have 144hz monitor.

  • 1) 120hz.
  • 2) Manage 3D Settings forced VSync adaptative 1/2 (game will run in 60hz VSync on)

Game Settings:

  • 1) Full Screen.
  • 2) Area chat off.

I do not know what exactly worked, but following these steps I have no more problems and the game runs smooth and the FPS remains like a solid rock.