Is a regex with (things|in|it) slow vs iterating a slice?

gistfile1.txt

$ go test -bench=.
goos: darwin
goarch: amd64
pkg: example.com/test
cpu: VirtualApple @ 2.50GHz
BenchmarkRegexOne-8     	18224203	        65.00 ns/op
BenchmarkSliceOne-8     	391034821	         3.078 ns/op
BenchmarkRegexThree-8   	12396331	        96.85 ns/op
BenchmarkSliceThree-8   	270857839	         4.426 ns/op
BenchmarkRegexFive-8    	11875524	       100.4 ns/op
BenchmarkSliceFive-8    	100000000	        10.85 ns/op
PASS
ok  	example.com/test	8.417s

test_test.go

package main

import (
	"regexp"
	"testing"
)

func regex(r *regexp.Regexp, s string) bool {
	return r.MatchString(s)
}

func iterate(slice []string, s string) bool {
	for _, m := range slice {
		if m == s {
			return true
		}
	}
	return false
}

func BenchmarkRegexOne(b *testing.B) {
	r, _ := regexp.Compile("(one|two|three|four|five)")
	for n := 0; n < b.N; n++ {
		regex(r, "one")
	}
}

func BenchmarkSliceOne(b *testing.B) {
	slice := []string{"one", "two", "three", "four", "five"}
	for n := 0; n < b.N; n++ {
		iterate(slice, "one")
	}
}

func BenchmarkRegexThree(b *testing.B) {
	r, _ := regexp.Compile("(one|two|three|four|five)")
	for n := 0; n < b.N; n++ {
		regex(r, "three")
	}
}

func BenchmarkSliceThree(b *testing.B) {
	slice := []string{"one", "two", "three", "four", "five"}
	for n := 0; n < b.N; n++ {
		iterate(slice, "three")
	}
}

func BenchmarkRegexFive(b *testing.B) {
	r, _ := regexp.Compile("(one|two|three|four|five)")
	for n := 0; n < b.N; n++ {
		regex(r, "five")
	}
}

func BenchmarkSliceFive(b *testing.B) {
	slice := []string{"one", "two", "three", "four", "five"}
	for n := 0; n < b.N; n++ {
		iterate(slice, "five")
	}
}