Launch Prism for heavy pages

pastacode-async.php

<?php
// add data-manual attribute, then call Prism in async way
add_filter( 'script_loader_tag', 'pastacode_async', 10, 3 );
function pastacode_async ( $tag, $handle, $src ) {
    if ( 'prismjs' == $handle ) {
        $tag = str_replace( '<script ', '<script data-manual ', $tag );
        $tag .= '<script>jQuery(document).ready(function($){Prism.highlightAll(true);});</script>';
    }
    return $tag;
}