What should I use, get_posts or wp_query for less CPU load?

Question

I have a blog and on the main page are 3 blocks of posts. So, I get these posts with "get_post" and I have 3 similar codes on page:

global $post;
$args = array( ... );
$myposts = get_posts( $args );
foreach( $myposts as $post ) :  setup_postdata($post); ?>
.......
<?php endforeach; ?>

I have a hight load of CPU and I wonder if I will use "wp_query" will save my CPU. Thanks.

Here are my get_posts() queries:

<?php
global $post;
$args = array( 'numberposts' => 5, 'offset'=> 0, 'category' => "1"   );
$myposts = get_posts( $args );
foreach( $myposts as $post ) :  setup_postdata($post); ?>
<div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
<?php the_title(); ?>
</div>
<?php endforeach; ?>

---

<?php
global $post;
$args = array( 'numberposts' => 7, 'offset'=>0, 'category' =>"2 , 4 , 6 , 7 , 9 ,10,11");
$myposts = get_posts( $args );

foreach( $myposts as $post ) :  setup_postdata($post); ?>
<div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
<?php the_post_thumbnail(array('size' => 300,300), array('title' => '')); ?>
</div>
<?php endforeach; ?>

---

<?php
$args = array( 'numberposts' => 15, 'orderby' => 'rand' ,'offset'=>0, 'category' =>"31");
$myposts = get_posts( $args );
foreach( $myposts as $post ) :  setup_postdata($post); ?>
<?php the_title(); ?>
</div>
  <?php endforeach; ?>

Answer 1

I doubt using get_posts() vs WP_Query() would make any meaningful/noticeable difference in CPU load. Ultimately, get_posts() is just a wrapper for WP_Query(), anyway:

$get_posts = new WP_Query;
return $get_posts->query($r);

You would be better served by looking at the efficiency of the queries themselves; but to provide specific assistance there, we would need to see each of your get_posts() queries.

Answer 2

All queries are eventually wrappers of WP_Query, and while some are better than other ( never use query_posts ), the performance differences of get_posts vs WP_Query are negligible.

The strict answer would be that WP_Query is faster, but the margin by which it's faster imperceptably small as to not be worth the optimisation.

If you have high CPU load, switching between get_posts and WP_Query is not the solution

I recommend viewing this slideset by the core developer Nacin that explains when and how queries should be used, and why:

http://www.slideshare.net/andrewnacin/you-dont-know-query-wordcamp-netherlands-2012