Netflix announced on March 3rd in Stuff that they were to launch Streaming Video services in New Zealand on the 24th March. With such short notice, ISPs had little time to forecast accurately, and install sufficient supply to meet demand.
In April, Vodafone Cable, Orcon & Slingshot all show a reduction in performance, at the time Netflix videos launched mid March. Our Youtube video download tests showed a significant drop in speed over that period. Note, these slower speeds may still be sufficient to view any video without interruption, depending on the connection speed.