Ajax load in function slow down page

Hi
Hi there
I have a question about the new function I put in the site, it’s ajax load more post for the custom post type, but I think it’s slow down my page load, the scroll thing take a while to finish, and click load more button need to wait for whole page load to actually function, is any way to avoid that, or make page load faster?

1. I thought maybe this code limited in only work for this template, how can I wrap this function using if( template_name){
}

function.php

//load more
add_action('wp_ajax_load_posts_by_ajax', 'load_posts_by_ajax_callback');
add_action('wp_ajax_nopriv_load_posts_by_ajax', 'load_posts_by_ajax_callback');

function load_posts_by_ajax_callback() {
    check_ajax_referer('load_more_posts', 'security');
    $paged = $_POST['page'];
    $args = array(
              'post_type'      => 'books',
              'post_status'    => 'publish',
              'posts_per_page' => 5,
              'order'          => 'DESC',
              'paged'          => $paged,				 
            );
    
    $my_posts = new WP_Query( $args );  
    if ( $my_posts->have_posts() ) :
        ?>
        <?php while ( $my_posts->have_posts() ) : $my_posts->the_post() ?>
 
            <?php get_template_part( 'template-parts/content', 'page' ); ?>
           
        <?php endwhile ?>
        <?php
    endif;
 
    wp_die();
}

My script code

     
	// {ID} is any unique name, example: b1, q9, qq, misha etc, it should be unique
	let ajaxurl = "<?php echo admin_url( 'admin-ajax.php' ); ?>";
	let page = 2;
        jQuery(function($) {
	   $('body').on('click', '.loadmore', function() {
		 var data = {
		'action': 'load_posts_by_ajax',
		'page': page,
		'security': '<?php echo wp_create_nonce("load_more_posts"); ?>',
		'max_page': '<?php echo $my_query->max_num_pages; ?>'
					        };
					   

		$.post(ajaxurl, data, function(response) {
		console.log()
		$('.content').append(response);
		    page++;    
                })
					        
		if(page == data['max_page']){
			$('.loadmore').fadeOut();
                }
           });
        });
</script>

Thank you guys so much