Lets give credit where credit is due. Since they capped this to 180 pax, the flight performance has improved.
What I have noticed though is NZ1 is still not consistently or close to consistently leaving JFK on time, with an average 1-2 hour delay, which in the evening in a very busy slot controlled airport is a problem.
NZ used to operate at LHR no? So I assume the crew knows the implications.
My guess is NZ still hasn't quite figured out the ground handling bugs yet.