Writing a program in C++ or Rust will not just make it use memory more efficiently than Go with the GC for free. Many Rust programs do a lot of heap allocations

Writing a program in C++ or Rust will not just make it use memory more efficiently than Go with the GC for free. Many Rust programs do a lot of heap allocations, and lots of people in C++ liberally use reference counted pointers which both require heap allocation and atomics. It is possible to write Go programs which efficiently use memory using object pooling just as you would in C. Go additionally can stack allocate many variables that would require a heap allocation in Java, where the GC is a much bigger issue.