if( !!(window.attachEvent && !window.opera) )		// detect IE
{
	var _getElementById;
	var _elemCache = {};

	// replace getElementById globally
	_getElementById = document.getElementById;
	document.getElementById = function(x) {
		return (_elemCache[x] = _elemCache[x] || _getElementById(x));
	}	
}

function clearPerfCache()
{
	if( !!(window.attachEvent && !window.opera) )		// detect IE
	{
		_elemCache = {};
	}
}