shawfactor

If you are sending large volumes of emails this is the plugin you need.
Generally wordpress emails are best sent by a third party, like gmauil or Sendgrid. But connecting and sending a large number of emails to third parties will slow your visitor experience down.
Unless those emails are sent in the background. This plugin does that.

LH Email Queue and Log

LH Email enables you to queu your emails so they are sent asynchronously.

Mahesh Thorat

Enhance your website’s performance and user experience with our Ajax Page Loading Plugin. Load content asynchronously without reloading the page, thanks to the power of AJAX. Enjoy seamless content updates and a smoother browsing experience with lightweight JavaScript implementation—no heavy JS frameworks required.
<h3>Key Features:</h3>
🔹 Seamless Content Updates: Load new content without refreshing the entire page, ensuring a fluid and uninterrupted user experience. 
🔹 Lightweight Implementation: Boost your website’s performance with minimal JavaScript, avoiding the bloat of heavy frameworks. 
🔹 Customizable JavaScript Callback: Leverage the <code>wp_ajax_load_complete</code> callback function for tailored JS hooks and custom behaviors.
<h3>JavaScript Callback Function</h3>
Use below callback function in your javascript library or you can just directly use * wp_footer * hook for add custom script.
<pre><code>wp_ajax_load_complete = function() {
 // YOUR JS HOOKS
}
</code></pre>

AJAX Loading

This plugin improves your users page experience without reloading pages using AJAX.

LH Email Queue and Log vs AJAX Loading