Both Go and Java are more likely going to have a faster development cycle for many developers than C++ and are less likely to have memory management bugs because they are garbage collected and memory safe[1]. Compared to many languages like Ruby, Python, etc all three of those are "high performance" languages. With a lot of optimization C++ has the potential to probably be the "fastest" solution. It all comes down to balancing execution performance, memory efficiency and development maintenance efforts.

While Go is a young language, I find working in it to be extremely productive, it makes concurrency easy to implement and get right, and produces application with good run-time characteristics.

[1]: http://en.wikipedia.org/wiki/Memory_safe

In general, Golang lets you code at higher level without compromising performance.