Fmt

tl;dr 基本的にio.Writer.Write()を使用するのが高速なようです。 result 1 2 3 4 5 6 $ go test -bench . -benchmem BenchmarkWrite-4 30000000 48.7 ns/op 16 B/op 1 allocs/op BenchmarkWriteWithBytes-4 500000000 3.95 ns/op 0 B/op 0 allocs/op BenchmarkFprintf-4 20000000 91.5 ns/op 0 B/op 0 allocs/op BenchmarkWriteTo-4 100000000 10.0 ns/op 0 B/op 0 allocs/op BenchmarkWriteWithBufferBytes-4 300000000 4.31 ns/op 0 B/op 0 allocs/op source 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 package main_test import ( "bytes" "fmt" "io" "net/http" "testing" ) var s = "Hello, my world" var bs = []byte(s) var buf = bytes.Buffer{} type NullWriter struct{} func (w *NullWriter) Write(b []byte) (int, error) { return len(b), nil } func BenchmarkWrite(b *testing.B) { var w io.Writer = &NullWriter{} b.ResetTimer() for i := 0; i < b.N; i++ { w.Write([]byte(s)) } } func BenchmarkWriteWithBytes(b *testing.B) { var w io.Writer = &NullWriter{} b.ResetTimer() for i := 0; i < b.N; i++ { w.Write(bs) } } func BenchmarkFprintf(b *testing.B) { var w io.Writer = &NullWriter{} b.ResetTimer() for i := 0; i < b.N; i++ { fmt.Fprintf(w, s) } } func BenchmarkWriteTo(b *testing.B) { var w io.Writer = &NullWriter{} b.ResetTimer() for i := 0; i < b.N; i++ { buf.WriteTo(w) } } func BenchmarkWriteWithBufferBytes(b *testing.B) { var w io.Writer = &NullWriter{} b.ResetTimer() for i := 0; i < b.N; i++ { w.Write(buf.Bytes()) } }