Magento“$ this-> loadLayout（）”在AJAX中消耗很长时间

I am new to magento & I wanted to add “AJAX cart” functionality to the my new site. Then I have followed the this tutorial . http://excellencemagentoblog.com/blog/2011/10/04/magento-add-product-to-cart-ajax/

But I have noted it has taken long time to respond. The reason is “$this->loadLayout()” consumes long time in following code.

$this->loadLayout();
$sidebar = $this->getLayout()->getBlock('cart_sidebar')->toHtml();

After spending some time in google I have changed my code to fallowing.

$sidebar = $this->getLayout()->createBlock('checkout/cart_sidebar')->setTemplate('path_my _template.phtml')->toHtml();

Then the time was reduced from 20 seconds to 5 seconds. The output was same in both codes except the url’s. I am printing (echo) the “checkout URL” in my template. In the First code the URL was ended with “?__SID” But not in the Second code.

Do anyone have an idea why this happen? I want to reduce the the item adding time and the get the secure URL as well.

I have solved the issue by changing the code as fallows.

$this->getLayout()->createBlock('page/html');
$sidebar = $this->getLayout()->createBlock('checkout/cart_sidebar')->setTemplate('path_my _template.phtml')->toHtml();