diff --git a/src/wp-includes/kses.php b/src/wp-includes/kses.php
index 7928f6d57a..157be6be11 100644
--- a/src/wp-includes/kses.php
+++ b/src/wp-includes/kses.php
@@ -1686,7 +1686,16 @@ function wp_kses_check_attr_val( $value, $vless, $checkname, $checkvalue ) {
  * @return string Filtered content.
  */
 function wp_kses_bad_protocol( $content, $allowed_protocols ) {
-	$content    = wp_kses_no_null( $content );
+	$content = wp_kses_no_null( $content );
+
+	// Short-circuit if the string starts with `https://` or `http://`. Most common cases.
+	if (
+		( str_starts_with( $content, 'https://' ) && in_array( 'https', $allowed_protocols, true ) ) ||
+		( str_starts_with( $content, 'http://' ) && in_array( 'http', $allowed_protocols, true ) )
+	) {
+		return $content;
+	}
+
 	$iterations = 0;
 
 	do {