I did an experiment. I turned on the AC and set it to 21C. After 1hr (when room temp was constant at 21C) i started the Cinebench R23 benchmark. The 30 minute result was at 6700 points. When the room is 29-30C the 30 minute test is at 5400 points.
I also observed that the powermetrics tool reported a 10W draw even during the late stages of the benchmark.
I haven't gamed on it because the room felt too cold (it's funny how it feels cold in the summer at 21C and when it's winter 21C feel warm).
I'm starting to think that the room temperature actually makes a big difference, but i still need to do a few experiments.