er... checking after the fact whether https://github.com/honeycombio/honeytail/commit/1ef49a2de43651954beea92c61b856449d09c4f3 was valid or not.Conclusion:

gistfile1.txt

$ go test -bench=. regcmp_test.go
testing: warning: no tests to run
BenchmarkNegativeMatchBool-8     	10000000	       118 ns/op
BenchmarkNegativeMatchString-8   	10000000	       128 ns/op
BenchmarkPositiveMatchBool-8     	 1000000	      2494 ns/op
BenchmarkPositiveMatchString-8   	  500000	      2878 ns/op
PASS
ok  	command-line-arguments	6.718s

regcmp_test.go

package main

import (
	"regexp"
	"testing"
)

var (
	reUser = regexp.MustCompile("^# User@Host: (?P<user>[^#]+) @ (?P<host>[^#]+).*$")
)

const (
	negative = "# Query_time: 0.000021  Lock_time: 0.000000 Rows_sent: 494  Rows_examined: 494"
	positive = "# User@Host: root[root] @ localhost []  Id:   233"
)

func BenchmarkNegativeMatchBool(b *testing.B) {
	for n := 0; n < b.N; n++ {
		reUser.MatchString(negative)
	}
}

func BenchmarkNegativeMatchString(b *testing.B) {
	for n := 0; n < b.N; n++ {
		reUser.FindStringSubmatch(negative)
	}
}

func BenchmarkPositiveMatchBool(b *testing.B) {
	for n := 0; n < b.N; n++ {
		reUser.MatchString(positive)
	}
}

func BenchmarkPositiveMatchString(b *testing.B) {
	for n := 0; n < b.N; n++ {
		reUser.FindStringSubmatch(positive)
	}
}