no manipulation with light counts (grouping/removing) will help with the noise on the floor. Unfortunately only thing that could help is an advanced adaptive sampler (currently not implemented), simplifying the ground material, or just letting it run longer. I could inspect the scene if you sent it to me to see what is causing the noise, but I cannot guarantee I will get to it any time soon.
edit: of course I am talking about reflections on ground, not about interior noise - reducing light count will work there. We are working on removing this limitation somewhere in version ~1.5ish.
