Just put this commands in the "in game" console and you will have much higher fps.
I went from 40 to 150fps on 1080p low settings.


r.VolumetricCloud 0 (deactivate clouds)

r.Fog 0 (this will deactivate fog)

grass.enable 0 (Disables Grass)

r.Streaming.PoolSize 0 (unlocks gpu memory)

r.Nanite.MaxPixelsPerEdge 4 (reduces triangles for nanite meshes)

r.Lumen.ScreenProbeGather.RadianceCache.ProbeResolution 16 (optimizes lumen)

r.DynamicGlobalIlluminationMethod 2 (disables Lumen)

r.ShadowQuality 0 (disables shadows)

r.Water.SingleLayer.Reflection 0 (disable water refelction)