Control the WordPress Heartbeat API without a plugin

Slow the WordPress Heartbeat down to once a minute with a few lines of code. Heartbeat Control can also stop it or set rules per area; here is the difference.

What Heartbeat Control does

Heartbeat Control lets you slow down or stop the WordPress Heartbeat API, with separate rules for the dashboard, the post editor and the front end. The plugin on WordPress.org

What the snippet does the same

Heartbeat checks with the server less often, which saves server work while the admin is open.
Post locks and login checks keep working, because Heartbeat still runs once a minute.

What's different

The snippet sets one interval, 60 seconds, wherever Heartbeat runs. The plugin can set different rules for the dashboard, the post editor and the front end.
The plugin can stop Heartbeat completely. The snippet only slows it down.
The plugin has a settings screen. With the snippet, you change the number of seconds in the code.

When to keep the plugin Keep the plugin if you want to stop Heartbeat entirely or set different rules for different parts of the site.

The snippet: Slow down the Heartbeat API

While the admin is open, WordPress checks in with the server every 15 to 60 seconds. Once a minute is enough for post locks and login checks, and saves server work.

PHP

<?php

add_filter(
	'heartbeat_settings',
	static function ( $settings ) {
		$settings['interval'] = 60; // Seconds, between 15 and 120.
		return $settings;
	}
);

Notes, where it runs and what it was tested with

Switching from the plugin

Install the snippet in Snipfire (it arrives switched off).
Deactivate Heartbeat Control.
Switch the snippet on. Snipfire checks the code and test-loads your site first.
Check the page it affects, then delete the plugin.