One of the websites I work on was recently experiencing crazy high server load (over 30!). Almost everything was a bot or crawler and wp-cron.php was being bombarded.

To deal with this I added define('DISABLE_WP_CRON', true); to the site's wp-config.php to disable WordPress' wp-cron scheduler and added the following cronjob to my server.

bash

*/1 * * * * /usr/bin/php /home/<user>/webapps/<application>/public/wp-cron.php > /dev/null 2>&1

WordPress' scheduler runs on every page load and checks to see if there are any crons that need to be run. So when your website is experiencing high traffic, whether that's from bots or real users, there's a chance WordPress could be running dozens or even hundreds of crons at a time.

Disabling WordPress management over the crons and moving that control to the server, ensures the crons are running systematically on a time based schedule.