diff --git a/.gitignore b/.gitignore
index 6c8d4e9..3f904fc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,6 @@ gron
 *.tgz
 *.swp
 *.exe
+cpu.out
+gron.test
+
diff --git a/CHANGELOG.mkd b/CHANGELOG.mkd
index 7eb91fb..c842422 100644
--- a/CHANGELOG.mkd
+++ b/CHANGELOG.mkd
@@ -1,5 +1,10 @@
 # Changelog
 
+## 0.1.6
+- Adds proper handling of key quoting using Unicode ranges
+- Adds basic benchmarks
+- Adds profiling script
+
 ## 0.1.5
 - Adds scripted builds for darwin on amd64
 
diff --git a/script/lint b/script/lint
index 57b8f45..58caf60 100755
--- a/script/lint
+++ b/script/lint
@@ -10,4 +10,4 @@ if [ $? -ne 0 ]; then
     gometalinter --install
 fi
 
-gometalinter --disable=gocyclo
+gometalinter --disable=gocyclo --disable=dupl
diff --git a/script/profile b/script/profile
new file mode 100755
index 0000000..4179d80
--- /dev/null
+++ b/script/profile
@@ -0,0 +1,7 @@
+#!/bin/sh
+set -e
+PROJDIR=$(cd `dirname $0`/.. && pwd)
+cd ${PROJDIR}
+
+go test -bench . -benchmem -cpuprofile cpu.out
+go tool pprof gron.test cpu.out
diff --git a/statements.go b/statements.go
index 397eb8b..bd72a98 100644
--- a/statements.go
+++ b/statements.go
@@ -3,7 +3,7 @@ package main
 import (
 	"encoding/json"
 	"fmt"
-	"regexp"
+	"unicode"
 )
 
 // The javascript reserved words cannot be used as unquoted keys
@@ -159,20 +159,48 @@ func formatValue(s interface{}) string {
 //     a key with spaces      -> true
 //     1startsWithANumber	  -> true
 func keyMustBeQuoted(s string) bool {
-	r := regexp.MustCompile(`^[a-zA-Z_][a-zA-Z0-9_]*$`)
-	if !r.MatchString(s) {
-		return true
-	}
-
-	// Check the list of reserved words
+	// Check the list of reserved words first
+	// to avoid more expensive checks where possible
 	for _, i := range reservedWords {
 		if s == i {
 			return true
 		}
 	}
+
+	for i, r := range s {
+		if i == 0 && !validFirstRune(r) {
+			return true
+		}
+		if !validSecondaryRune(r) {
+			return true
+		}
+	}
+
 	return false
 }
 
+// validFirstRune returns true for runes that are valid
+// as the first rune in a key.
+// E.g:
+//     'r' -> true
+//     '7' -> false
+func validFirstRune(r rune) bool {
+	return unicode.In(r,
+		unicode.Lu,
+		unicode.Ll,
+		unicode.Lm,
+		unicode.Lo,
+		unicode.Nl,
+	) || r == '$' || r == '_'
+}
+
+// validSecondaryRune returns true for runes that are valid
+// as anything other than the first rune in a key.
+func validSecondaryRune(r rune) bool {
+	return validFirstRune(r) ||
+		unicode.In(r, unicode.Mn, unicode.Mc, unicode.Nd, unicode.Pc)
+}
+
 // makePrefix takes the previous prefix and the next key and
 // returns a new prefix or an error on failure
 func makePrefix(prev string, next interface{}) (string, error) {
@@ -181,9 +209,11 @@ func makePrefix(prev string, next interface{}) (string, error) {
 		return fmt.Sprintf("%s[%d]", prev, v), nil
 	case string:
 		if keyMustBeQuoted(v) {
-			return fmt.Sprintf("%s[%s]", prev, formatValue(v)), nil
+			// This is a fairly hot code path, and concatination has
+			// proven to be faster than fmt.Sprintf, despite the allocations
+			return prev + "[" + formatValue(v) + "]", nil
 		}
-		return fmt.Sprintf("%s.%s", prev, v), nil
+		return prev + "." + v, nil
 	default:
 		return "", fmt.Errorf("could not form prefix for %#v", next)
 	}
diff --git a/statements_test.go b/statements_test.go
index 33898f8..8828da6 100644
--- a/statements_test.go
+++ b/statements_test.go
@@ -87,6 +87,7 @@ func TestKeyMustBeQuoted(t *testing.T) {
 		{"dotted", false},
 		{"dotted123", false},
 		{"_under_scores", false},
+		{"ಠ_ಠ", false},
 
 		// Invalid chars
 		{"is-quoted", true},
@@ -105,3 +106,102 @@ func TestKeyMustBeQuoted(t *testing.T) {
 		}
 	}
 }
+
+func TestValidFirstRune(t *testing.T) {
+	tests := []struct {
+		in   rune
+		want bool
+	}{
+		{'r', true},
+		{'ಠ', true},
+		{'4', false},
+		{'-', false},
+	}
+
+	for _, test := range tests {
+		have := validFirstRune(test.in)
+		if have != test.want {
+			t.Errorf("Want %t for validFirstRune(%#U); have %t", test.want, test.in, have)
+		}
+	}
+}
+
+func TestValidSecondaryRune(t *testing.T) {
+	tests := []struct {
+		in   rune
+		want bool
+	}{
+		{'r', true},
+		{'ಠ', true},
+		{'4', true},
+		{'-', false},
+	}
+
+	for _, test := range tests {
+		have := validSecondaryRune(test.in)
+		if have != test.want {
+			t.Errorf("Want %t for validSecondaryRune(%#U); have %t", test.want, test.in, have)
+		}
+	}
+}
+
+func BenchmarkKeyMustBeQuoted(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		keyMustBeQuoted("must-be-quoted")
+	}
+}
+
+func BenchmarkKeyMustBeQuotedUnquoted(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		keyMustBeQuoted("canbeunquoted")
+	}
+}
+
+func BenchmarkKeyMustBeQuotedReserved(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		keyMustBeQuoted("function")
+	}
+}
+
+func BenchmarkMakeStatements(b *testing.B) {
+	j := []byte(`{
+		"dotted": "A dotted value",
+		"a quoted": "value",
+		"bool1": true,
+		"bool2": false,
+		"anull": null,
+		"anarr": [1, 1.5],
+		"anob": {
+			"foo": "bar"
+		},
+		"else": 1
+	}`)
+
+	var top interface{}
+	err := json.Unmarshal(j, &top)
+	if err != nil {
+		b.Fatalf("Failed to unmarshal test file: %s", err)
+	}
+
+	for i := 0; i < b.N; i++ {
+		_, _ = makeStatements("json", top)
+	}
+}
+
+func BenchmarkMakePrefixUnquoted(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_, _ = makePrefix("json", "isunquoted")
+	}
+}
+
+func BenchmarkMakePrefixQuoted(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_, _ = makePrefix("json", "this-is-quoted")
+	}
+}
+
+func BenchmarkMakePrefixInt(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_, _ = makePrefix("json", 212)
+	}
+}
diff --git a/testdata/three.json b/testdata/three.json
new file mode 100644
index 0000000..fe2838d
--- /dev/null
+++ b/testdata/three.json
@@ -0,0 +1,16 @@
+{
+  "one": 1,
+  "two": 2.2,
+  "three-b": "3",
+  "four": [1,2,3,4],
+  "five": {
+    "alpha": ["fo", "fum"],
+    "beta": {
+      "hey": "How's tricks?"
+    }
+  },
+  "abool": true,
+  "abool2": false,
+  "isnull": null,
+  "ಠ_ಠ": "yarly"
+}