2 files changed, 29 insertions, 2 deletions
diff --git a/modules/caddyhttp/matchers.go b/modules/caddyhttp/matchers.go
index a4f4502..eaf43e9 100644
--- a/modules/caddyhttp/matchers.go
+++ b/modules/caddyhttp/matchers.go
@@ -24,6 +24,7 @@ import (
 	"path/filepath"
 	"regexp"
 	"sort"
+	"strconv"
 	"strings"
 
 	"github.com/caddyserver/caddy/v2"
@@ -935,14 +936,14 @@ func (mre *MatchRegexp) Match(input string, repl *caddy.Replacer) bool {
 
 	// save all capture groups, first by index
 	for i, match := range matches {
-		key := fmt.Sprintf("%s.%d", mre.phPrefix, i)
+		key := mre.phPrefix + "." + strconv.Itoa(i)
 		repl.Set(key, match)
 	}
 
 	// then by name
 	for i, name := range mre.compiled.SubexpNames() {
 		if i != 0 && name != "" {
-			key := fmt.Sprintf("%s.%s", mre.phPrefix, name)
+			key := mre.phPrefix + "." + name
 			repl.Set(key, matches[i])
 		}
 	}
diff --git a/modules/caddyhttp/matchers_test.go b/modules/caddyhttp/matchers_test.go
index 5163df1..950020f 100644
--- a/modules/caddyhttp/matchers_test.go
+++ b/modules/caddyhttp/matchers_test.go
@@ -692,6 +692,32 @@ func TestHeaderREMatcher(t *testing.T) {
 	}
 }
 
+func BenchmarkHeaderREMatcher(b *testing.B) {
+
+	i := 0
+	match := MatchHeaderRE{"Field": &MatchRegexp{Pattern: "^foo(.*)$", Name: "name"}}
+	input := http.Header{"Field": []string{"foobar"}}
+	var host string
+	err := match.Provision(caddy.Context{})
+	if err != nil {
+		b.Errorf("Test %d %v: Provisioning: %v", i, match, err)
+	}
+	err = match.Validate()
+	if err != nil {
+		b.Errorf("Test %d %v: Validating: %v", i, match, err)
+	}
+
+	// set up the fake request and its Replacer
+	req := &http.Request{Header: input, URL: new(url.URL), Host: host}
+	repl := caddy.NewReplacer()
+	ctx := context.WithValue(req.Context(), caddy.ReplacerCtxKey, repl)
+	req = req.WithContext(ctx)
+	addHTTPVarsToReplacer(repl, req, httptest.NewRecorder())
+	for run := 0; run < b.N; run++ {
+		match.Match(req)
+	}
+}
+
 func TestVarREMatcher(t *testing.T) {
 	for i, tc := range []struct {
 		desc       string