Hahahaha yes, but i have the solution, deactivate vsync in game throught the config menu, and save, now exit the game.
Go to your control panel nvdia, config "(witcher3.exe)" and set On the last 2 options, vertical sincronization (use ACTIVE, no other options) and set On Triple Buffer (this will boost the vertical sync speed).
Now Apply, and run the game (IN FULL SCREEN).
Let me know hows going now fps drops in interior

The game vsync is shit.