Was literally about to post the opposite :|

Just tried the game out after not having played for quite a while due to lacking a GPU.

Got an, average, GTX 1080 and am getting 70-80 FPS in Plains, 65-75 in meadows, with everything maxed @ 1440p

Performance wise, my setup is almost identical:
CPU: i5-9600KF (4.6GHz on all cores)
GPU: GTX 1080 (From an Aorus Gaming Box)
RAM: 16GB 3200MHz

GPU's are practically equivalent, my CPU is a tad faster, but it isn't going to 100% so it's a moot point.

Have you tried to run task manager, and see GPU utilization while playing? is it going to 100%?