I haven't seen in this article that studios are paying for that. It seems to me that it is in the interest of AMD/Nvidia to have the best performance for major

I haven't seen in this article that studios are paying for that. It seems to me that it is in the interest of AMD/Nvidia to have the best performance for major games, I would not be surprised that they do it for free, and are even asking for getting the games in advance to be able to prepare specific drivers.