i have the same poor results as you.
I have done a few tests with my PC but the performance of my graphics card is very poor. In comparison with other results I achieve a maximum of 50%.
What could be the problem?
GA-X399 Aorus Gaming 7 Gigabyte
AMD Threadripper 1950X
GTX 1080ti (GeForceDriver 391.35)
SSD 960 EVO 1TB m2
But i dont know where the problem is.
i've tried a lot already. other driver version. GPU overclocked. unfortunately I didn't feel any improvement.
a test in 3dmark works without problems with max. load