It can be tricky to get good frame rates with XP v11 - this primarily as XP runs with DX-11 and OpenGL. This API essentially uses a single core to communicate with the GPU. DX-12 isn't in the picture here - there are plans to re-write XP to use Vulkan, a cross-platform API that'll allow the use of multiple cores.
The system here: Asus ROG V10 motherboard with i7-6850K processor, 32G ram, all SSD storage, two nVidia GTX-1080's (each w/8G ram) in SLI surround driving three 4k monitors. On Win 10 64 bit.
With this computer system and most sliders set medium to high (no "ultra") and aliasing set to zero, I'll get 24-32 FPS depending upon the location. The only add-on I use is SkyMaxx Pro weather. Should note that the aircraft is the default C172.