@karol.osinski In the soon-to-be-release Kit 104.0 version, we will have a setting in the Common render settings allowing masking secondary rays (reflection and refraction) of lights which are set to ‘Visible In Primary Ray = False’ if a surface’s roughness is below a user-defined threshold.
This way you could still see your emissive light mesh fixture in the reflection and refraction, while the invisible light would only be sampled at higher surface roughness values where necessary for fast convergence/sampling.