Go is "lower level" in the sense that it depends much less on the JVM to optimize things for you. Go code maps much more neatly and predictably to machine code

Go is "lower level" in the sense that it depends much less on the JVM to optimize things for you. Go code maps much more neatly and predictably to machine code because the optimizations are fewer and less aggressive (e.g., Go has semantics for memory layout). This doesn't imply that Go is inherently faster than Java, but it's easier to reason about the performance of Go code.