As your whole post is based on this assumption, you should probably start by explaining where did you get this information from and/or whether you tried to run some benchmarks by yourself.
I never used Go, but I believe JVM is one of the fastest runtimes ever invented. In most cases its performance is comparable to highly optimized C++ code or supersedes it. It probably won’t be the best for cases like e.g. image processing (lack of pointers and direct memory access) and it usually consumes much more memory than C++, but in general it is pretty good performance-wise.