I would reccomend you turn GI off. Global Illumination is designed to bounce photons off of surfaces to mimic real light conditions. Interior settings like Kitchens, bathrooms, living rooms are what it is used for, and to get the most out of GI, you need to use Mental Ray photon shaders or custom written mental ray shaders.

For your slot machine, I reccomend you use ambient and Point light sources with the intensity levels set at zero with shadows turned on. This would just merely be an addition to your HDRI. These of course are just suggestions and I reccomend you do some experimentations.

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