I arrived at PHX on May 12 from LHR. OK, being in business class, I was off the aircraft fairly quickly, but the wait was under 5 minutes. Biggest delay once I got to the desk was the lady coming round to clean the fingerprint screen. Very pleasant lady, too.
I suspect that a lot depends on the airport and the arrival time: PHX doesn't seem to have many international arrivals at around 5pm and so is quick.