Optimizing Query used for a Shortcode

I see a few things that you might try to shortcut things:

1. Currently a Multisite network only allows one site ID, according to the Codex page for $wpdb->siteid. Also, the site ID is defined in your wp-config.php file as a constant, BLOG_ID_CURRENT_SITE. So any reference to $wpdb->siteid can be replaced by BLOG_ID_CURRENT_SITE.

2. Look into the new-in-3.7 function wp_get_sites(). It should be able to replace your $query = "SELECT * FROM $wpdb->blogs WHERE 1=1 "; and so forth.

3. Instead of using restore_current_blog() after every switch_to_blog(), what you can do is something like this:

   $current_blog = get_current_blog_id();
   foreach( $site_results as $blog ) {
       switch_to_blog( $blog );
       .
       .
       .
   } // end of your foreach()
   switch_to_blog( $current_blog );
   

If I’m reading your code right, you should be able to replace any $wpdb calls with those two points. See this answer (point #3) as well — “Don’t query if you got a template tag to do the job for you”.

References

• wp_get_sites()
• get_current_blog_id()