Forza isn't known for being particularly difficult to run on PC, but you never know these days. So it's a relief to find that the Forza Horizon 6 system requirements are pretty light for a reportedly stable 60 fps.
You should be able to run the game at playable frame rates with only 16 GB of RAM and a GPU and CPU that are multiple generations old. Even getting the most out of this game shouldn't require the absolute best graphics card or CPU on the market.
