Defer parsing of JavaScript Magento - Disable Sliders

I'm trying to improve my PageSpeed for my Magento website. I'm using GTmetrix about the test. I'm editing the file Head.php under app/code/core/Mage/Page/Block/Html

how this blog show me: http://www.magentocommerce.com/boards/m/viewthread/369412/#top

I replace this code in line 203:

// static and skin javascripts
            $html .= $this->_prepareStaticAndSkinElements('<script type="text/javascript" defer src="%s"%s></script>' . "\n",
                empty($items['js']) ? array() : $items['js'],
                empty($items['skin_js']) ? array() : $items['skin_js'],
                $shouldMergeJs ? array(Mage::getDesign(), 'getMergedJsUrl') : null
            );

            // If Mage is Admin
            if (Mage::app()->getStore()->isAdmin()) {
                $html .= $this->_prepareStaticAndSkinElements('<script type="text/javascript"  src="%s"%s></script>' . "\n",
                empty($items['js']) ? array() : $items['js'],
                empty($items['skin_js']) ? array() : $items['skin_js'],
                $shouldMergeJs ? array(Mage::getDesign(), 'getMergedJsUrl') : null
            );
            }

In this way the consecutive test is very good (100%) but The sliders on the page missing.

Can anyone help me? please