I've activated hardware accelerated gpu planing in win10 and set rF2 to high performance in the graphival settings
Maybe the GPU VRAM runs out? Try to set the graphics a bit lower. Or just test an another track, maybe Bathurst is a VRAM eater, like LeMans (I didn't tested Bathurst yet, so I am not sure if it is). + check windows 10 power plan, it should be on balanced/ryzen balanced, or high performance.