Great advices, the info from CDPR support might also be worth mentioning at this point:
Welcome to CD PROJEKT RED Technical Support! Here you will find help regarding our games and services, as well as answers to frequently asked questions.
support.cdprojektred.com
Also, in some cases installing a much older GPU driver version might work better. The game is pretty old already and newer drivers sometimes cause new issues for the game.
Starting the game in compatibility mode could also be an idea (for example, Windows 7 compatibility mode)