Zero-copy is totally underrated. Like the site alludes to, Go's interfaces make it reasonably accessible to write zero-copy code but it still needs some careful crafting. The payoff is great though, I've often been surprised by how much time is spent allocating and shuffling memory around.
I once built a proxy that translated protocol A to protocol B in Go. In many cases, protocol A and B were just wrappers around long UTF-8 or raw bytes content. For large messages, reading the content into a slice then writing that same slice into the outgoing socket (preceded and followed by slices containing the translated bits from A to B) made a significant improvement in performance vs. copying everything over into a new buffer.
Go's network interfaces and slices makes this kind of thing particularly simple - I had to do the same thing in Java and it was a lot more awkward.