1.remove render blocking JS (tentative, not ideal)

1.1 Insert following extra script in header.php just above <?php wp_head(); ?>  in both of child2 and child theme.

<script type=’text/javascript’ src=’http://japansightseeingtour.jp/wp-includes/js/jquery/jquery.js?ver=1.12.4′ async></script>

1.2.Insert the following in functions.php in both of child themes.

// Begin Custom Scripting to Move JavaScript from the Head to the Footer

function remove_head_scripts() {
remove_action(‘wp_head’, ‘wp_print_scripts’);
remove_action(‘wp_head’, ‘wp_print_head_scripts’, 9);
remove_action(‘wp_head’, ‘wp_enqueue_scripts’, 1);

add_action(‘wp_footer’, ‘wp_print_scripts’, 5);
add_action(‘wp_footer’, ‘wp_enqueue_scripts’, 5);
add_action(‘wp_footer’, ‘wp_print_head_scripts’, 5);
}
add_action( ‘wp_enqueue_scripts’, ‘remove_head_scripts’ );

// END Custom Scripting to Move JavaScript

2. Activate “autoptimize”.