In my case Netflix performance problems (via Comcast) were certainly happening before the ruling. 18 months ago Netflix was responsive; video started quickly and never stalled during play. During the last year there is usually at least one interruption during any given hour when the steam runs dry. It hasn't gotten noticeably worse since the ruling. Claims that the ruling created these problems seem like hysteria to me.
As for the "Super HD" and 3D video theory; that seems plausible. It seems like it's Netflix servers that struggle, as opposed to network congestion; streams stall and then suddenly recover and work fine as if their system is overloaded and shifts clients to usable capacity.
If high definition video is a contributor then this is self inflicted and deeply stupid. Cord cutters aren't trying to improve their media fidelity. Why compromise the performance of your service by overloading your system with HD content when your customer has already proven to be largely indifferent to HD? In all likelyhood the typical Netflix subscriber is the same person that still hasn't bothered to get a Blu-ray player.
That's certainly true in my case. A name-brand blu-ray is what? $50-100? It's not like I can't afford it. I could have a tower of the things if I wanted. I just don't care.