Java is faster to build than C++ almost all of the time. Header files (especially with templates) tend to turn C++ in to an O(n^2) run time, often running into hours.
OK, the only thing I can compare it against is my current "java" build times, and I can tell you that using maven is somewhat slow. So I guess you could say that if people went to java from c++ for the improved build times, they might still be interested in Go for the same improvement over java :)