It's starting to feel like a Start Green year. Some people have had really good luck with Start Green, but I'm only lukewarm on it. Toko used to have a pretty good blue wax that I thought outperformed Start Green and Swix LF4 is a pretty darn good wax for cold conditions as well.
The fact is, when it's super ridiculously cold you're just not going to have great glide. You're not going to be able to breathe all that well and your nose is going to turn black and fall off about halfway through the race as well (grrr...can you tell I'm ready to do some ski races in 20+ degree temperatures).
Actually, the last two races I've done have been a balmy 2 degrees at the start time. It's not that hard to deal with actually, you just do a fifteen minute warm-up while wearing your ski jacket and warm-up pants over your ski suit. Then, you peel off this additional layer 15 minutes before the start, do another quick ski, and, try to make sure you're only standing and shivering before the gun for about 5 minutes (no more than 5).
Once the race has started, you'll be too out of breath to worry about being cold. You can't breathe when it's cold...
I don't know about the rest of you, but I celebrate the day I can throw my Start Green down into the bottom of my wax box and just forget about it.