I have a weird mouse issue in the game. SImply said at random places the mouse movement becomes very unresponsive, for example I hold the shift and W keys (for Geralt to run forwards) and if I start moving the mouse to the left or right and stop, the character continues to bank into the direction I was pointing him to, if I suddenly change the movement direction by moving the mouse into the opposite direction, the character does not react, until several seconds later, when surrenly the camera pans into the other direction. This happens randomly nad I tired several mice, (one of which has variable DPI settings and oll of that stuff, no combination seems to wirk so far). I tired to reinstall the game, (both the normal and GOTY edition, have the lates drivers etc. I'm using an Alienware 15 with the 970m and 6GB of ram.
Any suggestions on how to fix this?

<Edit> disabling the GOG overlay fixed the issue....

This is more like keyboard input problem.
I have exactly the same issue - whenever any key is pressed game starts to lag.
Even when standing still and pressing left shift(default keybind, in this case basically does nothing) introduces severe lag.

Disabling in-game overlay solved it. But there is definitely bug somewhere.

Using Ryzen 7, Radeon 7850 2GB, 16GB DDR4, SSD + Win7x64. I've tried HW cursor on/off, fullscreen / borderless window...