I'm surprised that you can't just lock the game's threads to a smaller number of cores, but I can imagine the DRM some games ship with preventing you from doing

I'm surprised that you can't just lock the game's threads to a smaller number of cores, but I can imagine the DRM some games ship with preventing you from doing it. Booting up a VM with its core count limited is a clever workaround... I'm guessing a Windows VM would have reduced GPU performance because of the way pass-through works.