子菜单导航切换错误

我有一个主导航菜单，在悬停时出现子菜单，我的问题是，当悬停时，菜单子菜单在滑动和淡出状态之间闪烁，这是由它的功能(menuHover)提供的-我有一个可以在这里查看的fiddle

函数本身是:

    ///<summary>
    ///drop down menu navigation
    ///</summary>
    var menuHover = {
        //initialise our function
        init: function(){
            var menuItem = $(".navItem");                       
            //each menu item
            menuItem.each(function(){
                //checks to see if we have sub-navigation items             
                var $this = $(this),
                    hasSub = $this.children(".subNav"),
                    isSub = hasSub.length > 0;
                //toggle visibility on sub items when hovered               
                   if(isSub){              

                   $this.hover(
                   //on hover
                   function(){

                        hasSub.slideDown("fast");

                   }, 
                   // off hover
                   function(){

                        hasSub.fadeOut(350);

                   });                     

                   }

            }); 

        }
    };

任何帮助将不胜感激!