now i have an rtx 3070 and a 5800x3d but in january i had a 5700xt and i was getting like 100fps when dropping from the bus to reckless railways. in this months even if i'm on an nvidia gpu, i discovered some things which can probably improve fps:
-uninstall amd drivers.
-Install amd legacy dx11 drivers.
-disable dxnavi (only works for rx 6000 series or older if legacy drivers are installed).
-turn on shader cache.
-to improve gpu usage try tessellation on the amd software to ovverride application and set 64x or lower (this should boost fps in some games) and also try anisotropic filter which improves the quality on textures that appear to be far away and set this to 16x or lower. the amd software says that anisotropic filter only works in dx9 titles but
try it anyway, if it does nothing (search online how to turn on trilinear textures in fortnite, if it's possible then turn on anisotropic filter).
-disable ulps (do this possibly with registry editor).
-with more power tool disable all the DS_ which make the gpu to downclock and set the minimum gpu frequency on the AMD software to 100mhz less than the max.
to do everthing perfectly look for a tutorial on yt on the first, second, third, fifth and sixth point.
let me know the result.