Add benchmark details

Author: isingh

strings_bench_test.go renamed to strings_concat_bench_test.go

@@ -6,6 +6,54 @@ import (
 	"unsafe"
 )
 
+/*
+Benchmark results are in concat_bench.txt
+Concat - Our implementation (wrapper around strings.Builder
+Join - Using strings.Join
+Builder - Directly using strings.Builder
+Manual - A very efficient way using manual buffer copy. As of 1.13 is barely faster than our Concat, but we prefer this since it uses standard library
+
+❯ go test -bench=. -benchmem
+goos: darwin
+goarch: amd64
+pkg: github.com/wastedcode/strutils
+BenchmarkConcatSmall-16                 36458156                27.8 ns/op             3 B/op          1 allocs/op
+BenchmarkConcatJoinSmall-16             34108449                34.7 ns/op             3 B/op          1 allocs/op
+BenchmarkConcatBuilderSmall-16          35770252                29.8 ns/op             8 B/op          1 allocs/op
+BenchmarkConcatManualSmall-16           43085545                25.7 ns/op             3 B/op          1 allocs/op
+BenchmarkConcatMid-16                   29700308                35.1 ns/op            32 B/op          1 allocs/op
+BenchmarkConcatJoinMid-16               25948977                44.1 ns/op            32 B/op          1 allocs/op
+BenchmarkConcatBuilderMid-16            13468004                85.5 ns/op            56 B/op          3 allocs/op
+BenchmarkConcatManualMid-16             33127766                33.8 ns/op            32 B/op          1 allocs/op
+BenchmarkConcatLong-16                  22853175                51.6 ns/op            48 B/op          1 allocs/op
+BenchmarkConcatJoinLong-16              15723216                73.3 ns/op            48 B/op          1 allocs/op
+BenchmarkConcatBuilderLong-16           10799188               109 ns/op             112 B/op          3 allocs/op
+BenchmarkConcatManualLong-16            22404008                50.8 ns/op            48 B/op          1 allocs/op
+BenchmarkConcatLarge-16                 26872747                41.5 ns/op           112 B/op          1 allocs/op
+BenchmarkConcatJoinLarge-16             21745833                47.2 ns/op           112 B/op          1 allocs/op
+BenchmarkConcatBuilderLarge-16          14940462                74.7 ns/op           192 B/op          2 allocs/op
+BenchmarkConcatManualLarge-16           27793780                40.3 ns/op           112 B/op          1 allocs/op
+
+benchstat results
+name                   time/op
+ConcatSmall-16         27.4ns ± 5%
+ConcatJoinSmall-16     36.6ns ± 8%
+ConcatBuilderSmall-16  31.5ns ± 3%
+ConcatManualSmall-16   27.1ns ± 4%
+ConcatMid-16           38.2ns ± 5%
+ConcatJoinMid-16       47.0ns ± 3%
+ConcatBuilderMid-16    93.5ns ± 8%
+ConcatManualMid-16     36.2ns ± 4%
+ConcatLong-16          55.8ns ± 8%
+ConcatJoinLong-16      79.7ns ± 8%
+ConcatBuilderLong-16    114ns ± 7%
+ConcatManualLong-16    54.7ns ± 3%
+ConcatLarge-16         44.5ns ± 5%
+ConcatJoinLarge-16     49.6ns ±10%
+ConcatBuilderLarge-16  78.1ns ± 0%
+ConcatManualLarge-16   42.3ns ± 1%
+*/
+
 var concatResult string
 
 func concatStringsJoin(strs ...string) string {