Factorio is an indie game, I guess it might not be easy for indie developers to make use of multithreading, whereas AAA game developers have entire teams dedicated to engine development and multithreading.
Anyway, traditional graphics APIs like OpenGL are practically single-threaded. Modern APIs like DX12 and Vulkan have been designed with multithreading in mind and support scaling with number of cores much better (with added overhead of having to do manual synchronization).
Anyway, traditional graphics APIs like OpenGL are practically single-threaded. Modern APIs like DX12 and Vulkan have been designed with multithreading in mind and support scaling with number of cores much better (with added overhead of having to do manual synchronization).