VDB Rendering as cheap as possible for Flames

Currently I’m experimenting with rendering VDB fire (no smoke) and I’ve been trying to get the cost for the rendering down. If I turn off emissive, I see that it’s still self shadowing. Is it possible to disable this to make it cheaper on the GPU? I tried disabling everything I could find. I see in the GPU Visualizer that the HeterogeneousVolumes “RenderSingleScattering… (Light = none)”

Thanks