Often slow performance and errors on WooCommerce sites are caused by a high number of AJAX requests. If you are running a WooCommerce site on WP Engine and notice a high number of AJAX requests, disabling Cart Fragments AJAX may help improve your site’s stability.
What are WooCommerce Cart Fragments?
On sites that run WooCommerce, Cart Fragments is a script that uses Admin-Ajax to update the shopping cart without refreshing the webpage. However, this functionality may slow down the speed of your site or break caching on pages that may not require shopping cart information.
For example, Cart Fragments on static posts, pages, custom post types and feed pages that contain no eCommerce functionality may decrease cacheability and degrade site performance.
You can identify the Cart Fragments on a site on WP Engine’s Page Performance Tool, web page speed test, or your site’s Access Log with the following query argument added to your domain:
The Cart Fragments will appear as follows in your Access Log available in the User Portal (http://my.wpengine.com)
31/Dec/2017:23:59:59 +0000|v1|126.96.36.199|www.testsite.wpengine.com|200|210|127.0.0.1:80|0.328|0.330|POST /?wc-ajax=get_refreshed_fragments HTTP/2.0||