Remove unneeded scripts, stylesheets, and fonts from loading on the EE4 transactions page. This will reduce the number of http requests. Useful for payment methods like Authnet SIM that post to the Transactions page. Since the Transactions page isn't displayed in the registration process it doesn't need to look pretty.

simple_ee_four_transactions_page.php

<?php
//* Please do NOT include the opening php tag, except of course if you're starting with a blank file

add_action('template_redirect', 'my_simple_ee_transactions_page');
function my_simple_ee_transactions_page() {
  if(class_exists('EE_Registry')) {
    if(isset(EE_Registry::instance()->CFG->core->txn_page_id)) {
      if(is_page(EE_Registry::instance()->CFG->core->txn_page_id)) {
        remove_all_actions('wp_enqueue_scripts');
        remove_all_actions('wp_head');
        remove_all_actions('wp_footer');
      }
    }
  }
}

simple_ee_three_transactions_page.php

<?php
//* Please do NOT include the opening php tag, except of course if you're starting with a blank file
//* Version for Event Espresso 3 sites

add_action('template_redirect', 'my_simple_ee_three_transactions_page');
function my_simple_ee_three_transactions_page() {
    $org_options = get_option('events_organization_settings');
    if (!empty($org_options['notify_url'])) {
        if(is_page($org_options['notify_url'])) {
            remove_all_actions('wp_enqueue_scripts');
            remove_all_actions('wp_head');
            remove_all_actions('wp_footer');
        }
    }
}