Streaming speeds abysmal

Hello,

I've had Cox for about a week now and while speedtest.net shows consistently 50-55Mbps downstream, every time I want to watch something on Netflix or OnDemand through DirecTV (which uses the internet for their VOD) it freezes, buffers constantly or in Netflix's case it lowers the quality to the point that it's blocky.

I purchased a new wireless router (Netgear N900) since it was about time to upgrade anyway and it makes no difference.