I'm at Windows 10 Pro 1709 16288.1 and game mode is worst than ever.
In games like Counter Strike Global Offensive, the game mode is messing with FPS and the mouse dpi\sensitivity. Whenever you do fast horizontal moves, seems like it changes the mouse sensitivity randomnly.
Is there any document where this "game mode" is explained in technical terms?
I've had a similar experience. I play Rainbow Six Siege. My mouse sensitivity is such that when I move my mouse from one end of the mouse pad to the other my character turns slightly but noticeably more than 270 degrees (using in game compass). After turning game mode on I realised the sensitivity seemed to be slightly lower. I tested to find out that when I turn game mode on, the sensitivity slightly decreases (to the point where the character turns almost exactly 270 degrees)