Parallelize Downloads

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 here for more information on Domain Sharding