Remove counting author posts on users.php

query-hook.php

<?php

function interceptQuery( $query ) {
    if ( $GLOBALS['pagenow'] === 'users.php' && strpos( $query, 'SELECT post_author, COUNT(*) FROM' ) === 0 ) {
        echo '<h3>count_many_users_posts disabled for performance reasons</h3>';
        return false;
    }

    return $query;
}

add_filter( 'query', 'interceptQuery' );