Magento Defer JavaScript

How I achieve 2.8s Load time in Magento as compare to 10s using the following In order to have Defer Javascript, Please change the following files page.xml, my page.xml is stored at

/home/domain/public_html/app/design/frontend/base/default/layout/page.xml

<block type="page/html_head" name="head" as="head">
<action method="addJs">prototype/prototype.js<params>async</params></action>
<action method="addJs">lib/ccard.js<params>async</params></action>
<action method="addJs">prototype/validation.js<params>async</params></action>
<action method="addJs">scriptaculous/builder.js<params>async</params></action>
<action method="addJs">scriptaculous/effects.js<params>async</params></action>
<action method="addJs">scriptaculous/dragdrop.js<params>async</params></action>
<action method="addJs">scriptaculous/controls.js<params>async</params></action>
<action method="addJs">scriptaculous/slider.js<params>async</params></action>
<action method="addJs">varien/js.js<params>async</params></action>
<action method="addJs">varien/form.js<params>async</params></action>
<action method="addJs">varien/menu.js<params>async</params></action>
<action method="addJs">mage/translate.js<params>async</params></action>
<action method="addJs">mage/cookies.js<params>async</params></action>

GTmetrix