The most demanding setting currently is the DynamicReflection_DownsampleFactor in the ReflectionSettings section of the reshade config menu (shift+F10) you want that to be 1.0
The second would be the iMXAOSampleCountin in the MXAO section if the above does not work try lowering this aswell (to change this you would need to edit the ReshadeConfig.ini or switch reshade to configuration mode in the config menu)
The third is the AmbientLight try disabling it completely (checkbox next to the AmbientLight.fx text)
