Well, I have not taken a look at the implementation yet, but java is certainly known for delivering a decent performance even if the programmer is a little careless regarding perfromance.

In Go on the other hand, doing simple 'mistakes' like declaring a variable inside a loop can bring you to performance hell:

Declaration in a loop:

        var sum int
        for i := 0; i < n; i++ {
                x := i + i
                sum = x - i
        }

Declaration outside the loop:

        var sum int
        var x int
        for i := 0; i < n; i++ {
                x = i + i
                sum = x - i
        }

Benchmark results:

  BenchmarkInLoop-8       2000000000               0.40 ns/op
  BenchmarkOutLoop-8      2000000000               0.47 ns/op

And the same is certainly true for C/C++.

Src: https://nopaste.xyz/?68c6800acd9200d6#mDstI36uBPBU4Td8k//GNC...