They're making the game Directx11 because supposedly most people are still on Windows 7. With Directx12, it requires Windows 10 or later. With the bulk of people not using Windows 10 for their own valid reasons, Frontier has decided to make the game Directx11.
That's the advantage of Directx12. I like Windows 7 but it's better to use the latest OS rather than an OS which is already 10 years old. The game will utilize all the cores your CPU has, but it will only efficiently use a mere ONE of your CPU cores, leaving the rest of your CPU cores hovering around 5-20% utilization. This is a simulation game, and simulation games could use some more efficiency and better communication between the CPU and GPU rather than this Directx11 thingy.
One way to help is to overclock your CPU. An overclocked Intel Core i7-6700k, 8700k, 9700k or Intel Core i9-9900k at 5Ghz may help, but is best watercooled, but there's only so much optimizing Frontier can do with Directx11. Another is not to go too craycray and build humongous zoos. It is a piece by piece game, and Directx12 would have done a noticeably better job.
