diff --git a/src/html/escape.go b/src/html/escape.go
index f50a4b937a79b..ab6fd1c7b4b34 100644
--- a/src/html/escape.go
+++ b/src/html/escape.go
@@ -57,8 +57,9 @@ var replacementTable = [...]rune{
 // unescapeEntity reads an entity like "<" from b[src:] and writes the
 // corresponding "<" to b[dst:], returning the incremented dst and src cursors.
 // Precondition: b[src] == '&' && dst <= src.
-// attribute should be true if parsing an attribute value.
-func unescapeEntity(b []byte, dst, src int, attribute bool) (dst1, src1 int) {
+func unescapeEntity(b []byte, dst, src int) (dst1, src1 int) {
+	const attribute = false
+
 	// http://www.whatwg.org/specs/web-apps/current-work/multipage/tokenization.html#consume-a-character-reference
 
 	// i starts at 1 because we already know that s[0] == '&'.
@@ -139,14 +140,14 @@ func unescapeEntity(b []byte, dst, src int, attribute bool) (dst1, src1 int) {
 		break
 	}
 
-	entityName := string(s[1:i])
-	if entityName == "" {
+	entityName := s[1:i]
+	if len(entityName) == 0 {
 		// No-op.
 	} else if attribute && entityName[len(entityName)-1] != ';' && len(s) > i && s[i] == '=' {
 		// No-op.
-	} else if x := entity[entityName]; x != 0 {
+	} else if x := entity[string(entityName)]; x != 0 {
 		return dst + utf8.EncodeRune(b[dst:], x), src + i
-	} else if x := entity2[entityName]; x[0] != 0 {
+	} else if x := entity2[string(entityName)]; x[0] != 0 {
 		dst1 := dst + utf8.EncodeRune(b[dst:], x[0])
 		return dst1 + utf8.EncodeRune(b[dst1:], x[1]), src + i
 	} else if !attribute {
@@ -155,7 +156,7 @@ func unescapeEntity(b []byte, dst, src int, attribute bool) (dst1, src1 int) {
 			maxLen = longestEntityWithoutSemicolon
 		}
 		for j := maxLen; j > 1; j-- {
-			if x := entity[entityName[:j]]; x != 0 {
+			if x := entity[string(entityName[:j])]; x != 0 {
 				return dst + utf8.EncodeRune(b[dst:], x), src + j + 1
 			}
 		}
@@ -166,26 +167,6 @@ func unescapeEntity(b []byte, dst, src int, attribute bool) (dst1, src1 int) {
 	return dst1, src1
 }
 
-// unescape unescapes b's entities in-place, so that "a&lt;b" becomes "a<b".
-func unescape(b []byte) []byte {
-	for i, c := range b {
-		if c == '&' {
-			dst, src := unescapeEntity(b, i, i, false)
-			for src < len(b) {
-				c := b[src]
-				if c == '&' {
-					dst, src = unescapeEntity(b, dst, src, false)
-				} else {
-					b[dst] = c
-					dst, src = dst+1, src+1
-				}
-			}
-			return b[0:dst]
-		}
-	}
-	return b
-}
-
 var htmlEscaper = strings.NewReplacer(
 	`&`, "&amp;",
 	`'`, "&#39;", // "&#39;" is shorter than "&apos;" and apos was not in HTML until HTML5.
@@ -208,8 +189,29 @@ func EscapeString(s string) string {
 // UnescapeString(EscapeString(s)) == s always holds, but the converse isn't
 // always true.
 func UnescapeString(s string) string {
-	if !strings.Contains(s, "&") {
+	i := strings.IndexByte(s, '&')
+
+	if i < 0 {
 		return s
 	}
-	return string(unescape([]byte(s)))
+
+	b := []byte(s)
+	dst, src := unescapeEntity(b, i, i)
+	for len(s[src:]) > 0 {
+		if s[src] == '&' {
+			i = 0
+		} else {
+			i = strings.IndexByte(s[src:], '&')
+		}
+		if i < 0 {
+			dst += copy(b[dst:], s[src:])
+			break
+		}
+
+		if i > 0 {
+			copy(b[dst:], s[src:src+i])
+		}
+		dst, src = unescapeEntity(b, dst+i, src+i)
+	}
+	return string(b[:dst])
 }
diff --git a/src/html/escape_test.go b/src/html/escape_test.go
index 3702626a3dccf..8b51a55409fa5 100644
--- a/src/html/escape_test.go
+++ b/src/html/escape_test.go
@@ -118,8 +118,10 @@ func TestUnescapeEscape(t *testing.T) {
 }
 
 var (
-	benchEscapeData = strings.Repeat("AAAAA < BBBBB > CCCCC & DDDDD ' EEEEE \" ", 100)
-	benchEscapeNone = strings.Repeat("AAAAA x BBBBB x CCCCC x DDDDD x EEEEE x ", 100)
+	benchEscapeData     = strings.Repeat("AAAAA < BBBBB > CCCCC & DDDDD ' EEEEE \" ", 100)
+	benchEscapeNone     = strings.Repeat("AAAAA x BBBBB x CCCCC x DDDDD x EEEEE x ", 100)
+	benchUnescapeSparse = strings.Repeat(strings.Repeat("AAAAA x BBBBB x CCCCC x DDDDD x EEEEE x ", 10)+"&amp;", 10)
+	benchUnescapeDense  = strings.Repeat("&amp;&lt; &amp; &lt;", 100)
 )
 
 func BenchmarkEscape(b *testing.B) {
@@ -151,3 +153,17 @@ func BenchmarkUnescapeNone(b *testing.B) {
 		n += len(UnescapeString(s))
 	}
 }
+
+func BenchmarkUnescapeSparse(b *testing.B) {
+	n := 0
+	for i := 0; i < b.N; i++ {
+		n += len(UnescapeString(benchUnescapeSparse))
+	}
+}
+
+func BenchmarkUnescapeDense(b *testing.B) {
+	n := 0
+	for i := 0; i < b.N; i++ {
+		n += len(UnescapeString(benchUnescapeDense))
+	}
+}