WHAT? Hours to render? For a game model? Sorry, but that needs to render in under a second or a bit more, not more then 2-3 seconds a frame. you dont need to be using MR or HDRI for that... software render.
And no active reflections either, use the reflected color and plug in a color map for the reflective color.
cya later,
Matt
Live the life you love, love the life you live