Benchmarking various ways of concatenating strings in Go

join_test.go

package join

import (
	"fmt"
	"strings"
	"testing"
)

var (
	testData = []string{"a", "b", "c", "d", "e"}
)

func BenchmarkJoin(b *testing.B) {
	for i := 0; i < b.N; i++ {
		s := strings.Join(testData, ":")
		_ = s
	}
}

func BenchmarkSprintf(b *testing.B) {
	for i := 0; i < b.N; i++ {
		s := fmt.Sprintf("%s:%s:%s:%s:%s", testData[0], testData[1], testData[2], testData[3], testData[4])
		_ = s
	}
}

func BenchmarkConcat(b *testing.B) {
	for i := 0; i < b.N; i++ {
		s := testData[0] + ":" + testData[1] + ":" + testData[2] + ":" + testData[3] + ":" + testData[4]
		_ = s
	}
}

Use the code from @RezaOptic above

go version go1.17 darwin/amd64

Results

goos: darwin
goarch: amd64
pkg: ***
cpu: Intel(R) Core(TM) i7-4980HQ CPU @ 2.80GHz
BenchmarkJoin-8                  	18044035	        74.59 ns/op	      16 B/op	       1 allocs/op
BenchmarkSprintf-8               	 3249290	       393.9 ns/op	      96 B/op	       6 allocs/op
BenchmarkConcat-8                	 6670018	       257.7 ns/op	      32 B/op	       4 allocs/op
BenchmarkConcatOneLine-8         	20360762	        94.10 ns/op	       0 B/op	       0 allocs/op
BenchmarkBuffer-8                	16493529	       102.2 ns/op	      64 B/op	       1 allocs/op
BenchmarkBufferWithReset-8       	29284802	        51.32 ns/op	       0 B/op	       0 allocs/op
BenchmarkBufferFprintf-8         	 2917341	       392.3 ns/op	      80 B/op	       5 allocs/op
BenchmarkBufferStringBuilder-8   	15469124	        93.51 ns/op	      24 B/op	       2 allocs/op