If you are GPU bottlenecked, I think lowering most settings (minus objects level of detail) should help a bit.
Quick reccomendations:
Objects LOD 100
Ambient Occlusion High
Windshield Effects High
Texture Supersampling 2x2
Shadowmaps 1536
Terrain Shadows 512
Full compilation of GPU intensive settings here:
However it is quite weird, I haven’t dropped much below 30 when GPU limited on a GTX 1080