How to check if a plugin using wp-ajax.php

My server CPU usage get limited easily beacause there is 400,000 calls of /wp-admin/admin-ajax.php.

I tried to turn off Heartbeat, but the problem is still there.

I am trying to track which plugins using admin-ajax.php and turn them off properly.

1. My method is to search for keywords ajaxurl and admin-ajax.php in all php file of plugins folder. Is that correct?

   • I found some plugin using that such as debug plugin, console debug plugin, jetpack, duplicator,…
   • There are too many plugins using admin-ajax.php. They keeps on calling admin-ajax.php .Please tell me how to fix this problem.

2. Will de-activate plugin completely turn off admin-ajax.php call? Or I need to delete completely that plugin?

Thank you very much.

Update 1:
I have just noticed that Debug Bar plugin maybe the problem. When I am at wp-admin, it keeps on showing notice related to jQuery error. In order to do that, maybe it use admin-ajax.php.

Anyway, I deleted the plugin and will check cpu usage in next few hour.