Help to locate a woocommerce hook method

We are migrating a working project from a centos server to a distributed environment in which databases, load-balancers, cache servers, and applications are on different machines.

I am trying to trace an issue in WordPress. When the user gets back from IPG, it takes quite a time to add note to order and it leads to a painful timeout afterward. I could trace the problem up until here:

wp-content/plugins/woocommerce/includes/class-wc-order.php

line 1723 reads:

            do_action(
                'woocommerce_new_customer_note',
                array(
                    'order_id'      => $this->get_id(),
                    'customer_note' => $commentdata['comment_content'],
                ) 
            ); /* It takes forever to complete */

Based on my limited knowledge of WordPress, woocommerce_new_customer_note is a hook that fails to fulfill its goal.

I need help in:

• finding where the woocommerce_new_customer_note hook sits and continue my debugging.
• Finding out why this code fails to execute

Side note: We are on ubuntu 18.04, LEMP stack, PHP-FPM 7.2