1. WooCommerce Fast Cart
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Will WooCommerce Fast Cart slow down my site?

The WooCommerce Fast Cart plugin has been designed with performance in mind. However, there may be situations where you find that the popup cart is opening slowly. This article will help you to find the cause of the problem.

Understanding Fast Cart and performance

The first step is to understand a bit more about how the popup cart works, and what could be affecting the load time.

The mini cart is generated dynamically in the background over AJAX, after the rest of the page has loaded.

The plugin adds one script and one stylesheet to the page. They load on every page because many themes display cart and checkout buttons on every page, and the the fast cart needs to be available on every page that has these. They are incredibly small files and you can reduce the impact even further by using a performance plugin such as WP Rocket or Autoptimize to combine and defer all the JavaScript on your site. However, this is unlikely to be the cause of any performance issues.

The main thing that could slow down WooCommerce Fast Cart is the fact that it makes two requests to the server when a product is added to the cart:

  1. First, to add the item to the cart.
  2. Second, to refresh the cart contents.

These requests cannot be cached because - by definition - they are user-specific and need to be loaded at the time.

Possible causes for slow load times

Most WooCommerce stores can add products to the cart very quickly so that the popup cart opens fast. However, if you have slow hosting and/or your site has wider performance problems (e.g. being overloaded with too many plugins or slow loading custom code) then the popup cart may take longer to load. This is due to the overall speed of the website, which mean that the two server requests take longer than they would on a faster website. It is not a specific problem with the plugin.

You can check this by using the 'Inspect Element' tool in Chrome to compare the speed of adding products to the cart with and without Fast Cart:

  1. Visit the website in Chrome.
  2. Right-click and select 'Inspect', then go to the 'Network' tab. Leave this open for the rest of the test (tip: reduce the size of the 'Inspect' panel so that you can see the website at the same time).
  3. Now perform the following 2 tests and write down the speed of each one:
    1. Add a product to the cart and make sure the Fast Cart opens automatically. In the 'Network' tab, find the tasks which are called something like '?add-to-cart=11639&wfc-cart=true' and '?wfc-cart=true'. This will tell you how long WooCommerce Fast Cart took to make the requests to the server.
    2. Next, deactivate the WooCommerce Fast Cart plugin and add a product to the cart. In the 'Network' tab, find the tasks which are called something like '?add-to-cart=11639' and '?cart'. Again, make a note of the speed.

Solving performance problems

Once you have recorded the speed of adding products to the cart with and without Fast Cart active, you need to see which one is slowest:

  • If Test 1 is significantly slower than Test 2, then this indicates a problem with WooCommerce Fast Cart and you should Contact Us for support.
  • If Test 2 is slower then it is a wider issue with the speed of your website. We recommend doing some general performance work to improve it. Here's a useful tutorial to get you started.

An example

To illustrate how this method helps you to identify whether speed issues are coming from Fast Cart, here are some screenshots from one of our customer's websites. This customer had reported issues with the popup cart loading slowly.

Test 1 - Using Fast Cart

Fast Cart performance
Test 1: Adding a product to the cart with Fast Cart set to auto-open

You can see the load time highlighted in yellow - the server requests to add the product to the cart took 1.58s and 1.75s.

For comparison, the same server requests take just 0.2s on the Fast Cart demo site, which is hosted on Kinsta. This is more than 7 times faster than on the customer's site, which was using basic shared hosting.

Test 2 - Fast Cart disabled

Without Fast Cart
Test 2: Adding a product to the cart with Fast Cart inactive

On this customer's website, adding products using Fast Cart is actually faster than using WooCommerce’s default behavior! This shows that there are wider performance problems which need to be investigated, rather than a specific issue with Fast Cart.

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