WordPress provides a handy solution to do AJAX calls – the admin-ajax.php file which is located in /wp-admin/. Sometimes AJAX calls can bloat your website and result in loading times which aren’t funny anymore.
You ask yourself now: How can I analyze this? How can I find the particular piece on my website which results in calling admin-ajax.php for seconds? I often read “Disable all plugins, enable one plugin and check the performance again.” Yep, that is definitely one way to start but even if you find the plugin that is responsible for calling admin-ajax.php sometimes it is not a solution to just delete the plugin.