The numerous performance and stability issues (not just in the containers, but also affecting the main cgroup / "host" rather badly) I had with Docker, but never with LXC, which, according to you would be pretty much the same thing - "just namespacing your process". But it isn't.

Docker is ok when it works, hell when it doesn't, has lots of bugs and regularly regresses. I don't understand why you'd run production infrastructure on that and not on any of the alternatives.