max performance not clock-down your gpu ( memory , etc ) , so it can never be cool-down in phases where it have not much work. If you not really notice a beneffit from that setting, then set it back to “normal”.
DX12, yes… can bring much more load on the gpu. Therefore as mentioned, set Vsync:50% which limits to 30fps in you case.
The Fenix, etc… I mentioned these are known CPU intensive. You can do some checks/compare with the default airplanes, like a C152/172. You should get a bitter better results.
Your laptop works well, for that what it is 
… But, also my “older” i7-8700k have a better performance than the laptop CPU. Its just not limited like a laptop cpu and so I also can use settings like “sync all cores”, what mean my cpu runs with 4.7 at all cores. Your Cpu have a turbo of 4.8, but only under specific conditions and not in overhead.