fix performance regression

lib/dao-factory.js

@@ -294,6 +294,9 @@ module.exports = (function() {
 
     Object.defineProperties(this.DAO.prototype, attributeManipulation)
     this.DAO.prototype.attributes = Object.keys(this.DAO.prototype.rawAttributes)
+    this.DAO.prototype._isAttribute = Utils._.memoize(function (key) {
+      return self.DAO.prototype.attributes.indexOf(key) !== -1
+    })
   }
 
   DAOFactory.prototype.sync = function(options) {

lib/dao.js

@@ -162,8 +162,8 @@ module.exports = (function() {
           this._setInclude(key, value, options)
           return
         } else {
-          // If not raw, and attribute is not in model definition
-          if (!options.raw && Object.keys(this.Model.attributes).indexOf(key) === -1) {
+          // If not raw, and attribute is not in model definition, return
+          if (!options.raw && !this._isAttribute(key)) {
             return;
           }