This piece of code works for me, but I have more than 10,000 posts in post types on my website, and by calling posts_per_page => -1
The loading speed of the site is very low and the RAM and CPU are heavily involved and become 100%.
I want to optimize this code so that there is no need to call posts_per_page => -1 and load all the posts in Admin Ajax.

function set_object_terms(){
    global $post;
    global $wp_taxonomies;
    $args = array(
        'post_type' => array('music','musicvideo','remix','palylist','album'),
        'post_status' => 'publish',
        'posts_per_page' => -1,
    );
    $index_posts = new WP_Query( $args );
    if( $index_posts->have_posts() ){
        while( $index_posts->have_posts() ){ $index_posts->the_post();
        $postid = get_the_ID();
        $terms = get_post_meta($postid,'meta_info_singername',true);
        if(is_array($terms) && !empty($terms)) : 
                $taxonomy = 'singers';
                $default_terms = array();
                foreach ($terms as $term_id) {
                    $tmp_term_id = get_term_by('id', $term_id, 'singers');
                    if ($tmp_term_id) {
                        $default_terms[] = (int) $tmp_term_id->term_id;
                        $default_terms[] = (int) $tmp_term_id->parent;
                    }
                }
                $defaults = array($taxonomy => $default_terms);
                $postid = get_the_ID();
                 wp_set_object_terms( $postid,$defaults[$taxonomy], $taxonomy);  
        else : 
            $postid = get_the_ID();
            $termids = '';
            $taxonomy = 'singers';
            wp_set_object_terms( $postid,$termids, $taxonomy);
        endif;
            
        }
        wp_reset_postdata();
    }
}
add_action('init', 'set_object_terms', 20 );