Using a "load more" button

Hello everyone. I hope I am posting at the correct category.

<div class="container">
  <?php foreach ( $myPosts as $post ) : setup_postdata( $post ); ?>
	<div class="thumbnail"><a href="<?php the_permalink(); ?>">
	<?php the_post_thumbnail('thumbnail' , array( 'class'	=> "aligncenter"));
         ?>
                <div class="image-title"><?php the_title(); ?></div>
	    </a>
        </div>
  <?php endforeach;
        wp_reset_postdata(); ?>
</div>

Well the above code, creates a container, in which all the posts of a specific category are shown (this is addressed when I create $myPosts and works fine). The result is fine, but obviously when the posts of a category are too many, the load page time increases. So I was thinking of using a “load more” button.

1st question: Is this the appropriate way of reducing the page load time in this case?

2nd question: How can I do this? I couldnt find an appropriate plugin, for this specific case, as I am showing the posts with my own code, without using a “posts page” or smth. If there is one and I haven’t noticed, then you ‘re most welcome.

Thanks!