You should do some reading on DX11 and DX12 before saying it is multithreaded. DX11 uses only one core for the draw calls. It is a ‘single core’ application. The CPU can only communicate with the GPU through a single core. Whatever thread that the CPU is using besides the main core that is related to the GPU is a secondary task that went through the main thread first.
So no, it is not multithreaded per se, since all draw calls have to go through the main thread first. Exactly what I said. The main thread can’t take too much. Other simulators go through the same problems. It is too much data to go through a single core first. The problem is, studios like Il-2 and DCS don’t have structure to code a true multithreaded code for DX12 (there is a PDF from Intel explaining how DX12 and multithreaded code is). It is not easy.
But Asobo has Microsoft behind, then a lot of people questioned the DX11 thing. So, going back, unless they recode it, the performance issues will persist and it is going to be a matter of what do we keep and what do we take out to give room for new stuff. Il-2 has been that way for years.
With DX12, we could have several main cores, and then GPUs like the 3090 could have a dance with some powerful CPUs.