This isn't an "app." It's one service that's a small but important piece of a rather large backend. It's essentially a content-aware WebSockets proxy. I want it to be extremely light weight with minimal latency addition (less than 1 msec, ideally).

So why C/C++? When it comes to language choice I have a very simple rule: use whatever I think I can be most successful with.

Go prescribes a particular concurrency model. C and C++ do not. I have many years of experience wielding C to write very small, very fast programs that do very big things. I have zero years of experience with Go. Go would be interesting if I was writing something more general purpose or something that needed lots of extensibility, or something on which I plan to collaborate with people who don't have a lot of concurrent programming experience. None of those cases apply.