By value vs by reference

benchmark_test.go

package main

import (
	"testing"
)

func byValue(d Data) Data {
	return d
}

func byPointer(d *Data) *Data {
	return d
}

func BenchmarkByValue(b *testing.B) {
	var data Data
	for i := 0; i < b.N; i++ {
		data = byValue(data)
	}
}

func BenchmarkByPointer(b *testing.B) {
	data := new(Data)
	for i := 0; i < b.N; i++ {
		data = byPointer(data)
	}
}

go.mod

module example.com

go 1.24.1

main.go

package main

import (
	"fmt"
	"unsafe"
)

type Data struct {
	V1  float64
	V2  float64
	V3  float64
	V4  float64
	V5  float64
	V6  float64
	V7  float64
	V8  float64
	V9  float64
	V10 float64
	V11 float64
	V12 float64
	V13 float64
	V14 float64
	V15 float64
	V16 float64
	V17 float64
	V18 float64
	V19 float64
	V20 float64
	V21 float64
	V22 float64
	V23 float64
	V24 float64
	V25 float64
	V26 float64
	V27 float64
	V28 float64
	V29 float64
	V30 float64
	V31 float64
	V32 float64
	V33 float64
	V34 float64
	V35 float64
	V36 float64
	V37 float64
	V38 float64
	V39 float64
	V40 float64
	V41 float64
	V42 float64
	V43 float64
	V44 float64
	V45 float64
	V46 float64
	V47 float64
	V48 float64
	V49 float64
	V50 float64
}

func main() {
	fmt.Println("Size of the structure: ", unsafe.Sizeof(Data{}), "bytes")
}

results.txt

$ go run .
Size of the structure:  400 bytes

$ go test -bench=. -benchtime=10s
goos: darwin
goarch: arm64
pkg: example.com
cpu: Apple M1 Pro
BenchmarkByValue-8     	742338524	        16.10 ns/op
BenchmarkByPointer-8   	1000000000	         0.3127 ns/op
PASS
ok  	example.com	14.146s