Actually, after a google search it seems the author (Replying to an user in another forum) is aware of the bug, that some Windows 10 users are experiencing an error related to graphics drivers, which makes the game try to render everything using only the CPU.
However, he also said that since he uses a really old machine, he cannot solve the issue because he doesn't have anything to try and test solutions.
So, it seems we are fucked until he updates his hardware, whether we blame Microsoft for breaking something along the way, or the guy for using Windows xp in 2017, is up in the air I guess.