2 files changed, 45 insertions, 4 deletions
diff --git a/src/bytes/bytes.go b/src/bytes/bytes.go
index 6fcebe6593..08fc14d837 100644
--- a/src/bytes/bytes.go
+++ b/src/bytes/bytes.go
@@ -759,7 +759,36 @@ func TrimRight(s []byte, cutset string) []byte {
 // TrimSpace returns a subslice of s by slicing off all leading and
 // trailing white space, as defined by Unicode.
 func TrimSpace(s []byte) []byte {
-	return TrimFunc(s, unicode.IsSpace)
+	// Fast path for ASCII: look for the first ASCII non-space byte
+	start := 0
+	for ; start < len(s); start++ {
+		c := s[start]
+		if c >= utf8.RuneSelf {
+			// If we run into a non-ASCII byte, fall back to the
+			// slower unicode-aware method on the remaining bytes
+			return TrimFunc(s[start:], unicode.IsSpace)
+		}
+		if asciiSpace[c] == 0 {
+			break
+		}
+	}
+
+	// Now look for the first ASCII non-space byte from the end
+	stop := len(s)
+	for ; stop > start; stop-- {
+		c := s[stop-1]
+		if c >= utf8.RuneSelf {
+			return TrimFunc(s[start:stop], unicode.IsSpace)
+		}
+		if asciiSpace[c] == 0 {
+			break
+		}
+	}
+
+	// At this point s[start:stop] starts and ends with an ASCII
+	// non-space bytes, so we're done. Non-ASCII cases have already
+	// been handled above.
+	return s[start:stop]
 }
 
 // Runes interprets s as a sequence of UTF-8-encoded code points.
diff --git a/src/bytes/bytes_test.go b/src/bytes/bytes_test.go
index 80a54f6118..98ba95009d 100644
--- a/src/bytes/bytes_test.go
+++ b/src/bytes/bytes_test.go
@@ -1617,9 +1617,21 @@ func BenchmarkFieldsFunc(b *testing.B) {
 }
 
 func BenchmarkTrimSpace(b *testing.B) {
-	s := []byte("  Some text.  \n")
-	for i := 0; i < b.N; i++ {
-		TrimSpace(s)
+	tests := []struct {
+		name  string
+		input []byte
+	}{
+		{"NoTrim", []byte("typical")},
+		{"ASCII", []byte("  foo bar  ")},
+		{"SomeNonASCII", []byte("    \u2000\t\r\n x\t\t\r\r\ny\n \u3000    ")},
+		{"JustNonASCII", []byte("\u2000\u2000\u2000☺☺☺☺\u3000\u3000\u3000")},
+	}
+	for _, test := range tests {
+		b.Run(test.name, func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				TrimSpace(test.input)
+			}
+		})
 	}
 }