SBT...no.. i have a first grader and kindergartner that have to be to school at 8:30 eastern.  so, i just have had little sleep instead of no sleep.  If I take the cube out of the scene.. the s/s go up to nearly 300k but the efficiency goes down to around 400% or so.  From what I can tell from the benchmarks(and JtheNinja can jump in any time); the true test of the speed you're getting from Lux is c/s not s/s because that is what all the benchmark speeds list.  Your c/s is your s/s multiplied by your efficiency.  So I would assume you want to hit the sweet spot of high s/s and high efficiency.  I've had some 4000% efficient renders look pretty sweet after a couple hundred passes; yet, have had some low efficiency-high s/s renders take a couple thousand to clear up.