The WordPress Heartbeat API uses /wp-admin/admin-ajax.php to run AJAX calls from the web-browser. While this is great and all it can also cause high CPU usage and crazy amounts of PHP calls. For example, if you leave your dashboard open it will keep sending POST requests to this file on a regular interval, every 15 seconds. Here is an example below of it happening.
We have built in the option to change the frequency at which this can poll your dashboard. You have the following options:
- 15 seconds (default)
- 30 seconds
- 45 seconds
- 60 seconds
We recommend using the 60-second option. This is what we use across all of our sites.
Make sure to also check out our other option to disable the Heartbeat API.