How to make my Web store much faster?

Hello friends, Can you recommend a wordpress template for batter design foe eCommerce website which are developed for online website extension shopping in magento, Joomla, Prestashop, openerp. Our website, Store the problem is that this site takes to load 7 seconds, what can I do to increase the loading speed of this site?. Recommend a batter security payment method for globally also.