David Garcia

We need to determine the subdomain pattern (ex: http://cdn-#.domain.tld ) substitution and the maximum number of subdomains we want to work with (ex: 5).
The pattern will transform an url like this ‘http://www.domain.tld/img/source1.jpg’ to this new url structure ‘http://cdn-X.domain.tld/img/source1.jpg’ where X ranges from 1 to 5 (max).
NOTE: If you have trouble accessing images using the new address because WordPress asks you to register the domain then you must insert the following line in the file wp-config.php
<pre><code>include_once(ABSPATH.'wp-content/plugins/domain-sharding/domain-sharding-alias.php'); 
</code></pre>
Then you need to be sure to set write permissions to the aliases folder located within the plugin directory.
NOTE: You’ll need to manually create the new A records for the subdomains in your DNS panel. They should have the same ip address of your main domain.
Visit the <a href="http://www.seocom.es/" rel="nofollow ugc">Seocom website</a> for more information about SEO or WPO optimization

Domain Sharding

This plugin modify the url of the images to speed up the page browsing.

Daryll Doyle

This plugin enables Parallelized Downloads / Domain Sharding for your WordPress images.
This is a good alternative if you don’t want to pay for a CDN but have an image heavy site.
Domain sharding is a technique used to increase the amount of simultaneously downloaded resources for a particular website by using multiple domains. 
This allows websites to be delivered faster to users as they do not have to wait for the previous set of resources to be downloaded before beginning the next set.
This plugin is only useful if you have an image heavy site. For sites with very few images you may see an increase in load times with this plugin due to increased numbers of DNS lookups.
See <a href="https://www.keycdn.com/support/domain-sharding/" rel="nofollow ugc">here</a> for more information on Domain Sharding

Parallelize Downloads

Enable Parallelized Downloads / Domain Sharding for your WordPress images.

Domain Sharding vs Parallelize Downloads