speedup Zend_Db quoteIdentifier

library/Zend/Db/Adapter/Abstract.php

@@ -48,7 +48,7 @@ require_once 'Zend/Loader.php';
  */
 abstract class Zend_Db_Adapter_Abstract
 {
-
+	protected static $_quoted_identifiers =  [];
     /**
      * User-provided configuration
      *
@@ -970,8 +970,10 @@ abstract class Zend_Db_Adapter_Abstract
     protected function _quoteIdentifier($value, $auto=false)
     {
         if ($auto === false || $this->_autoQuoteIdentifiers === true) {
+					if (isset(static::$_quoted_identifiers[$value]))
+						return static::$_quoted_identifiers[$value];
             $q = $this->getQuoteIdentifierSymbol();
-            return ($q . str_replace("$q", "$q$q", $value) . $q);
+            return static::$_quoted_identifiers[$value] = ($q . str_replace("$q", "$q$q", $value) . $q);
         }
         return $value;
     }