Wow, these are mighty impressive gains right there, didn't know Tomb Raider could yield such great increases under CPU bound conditions in DX12, though the DX12 path is marred by being inferior to DX11 image quality wise, as VXAO only works in DX11 and does wonders for shadows quality.
FWIW, I couldn't replicate your gains in The Division on my 1070 and i7 3770, so I am left wondering if it's a Ryzen thing?
Probably a "moar core" thingy