Wordpress launched 4.3 version and I upgraded it but now the CPU loads very high and the speed of website extremely slow. Then, I try to find solution and found this code. It works and my website back normal:

Open wp-includes/taxonomy.php file, and go to line 4448:
wp_schedule_single_event( 'wp_batch_split_terms', time() + MINUTE_IN_SECONDS );

Change to this:
wp_schedule_single_event( time() + MINUTE_IN_SECONDS, 'wp_batch_split_terms' );

Then, create a folder in wp-content and name it with mu-plugins (/wp-content/mu-plugins).

Create a file inside mu-plugins folder and name it with fix.php and paste this code:

<?php
function clear_bad_cron_entries() {
// Fix incorrect cron entries for term splitting
$cron_array = _get_cron_array();
if ( isset( $cron_array['wp_batch_split_terms'] ) ) {
    unset( $cron_array['wp_batch_split_terms'] );
        _set_cron_array( $cron_array );
   }
}
clear_bad_cron_entries();

Finish, website speed and CPU loads will back normal.


Update: Instead, please update your Wordpress 4.3 version to 4.3.1.