A Regional Edge Cache location lies between the main webserver and the

global edge location. When the popularity of an object/content decreases, the

global edge location may take it out from the cache.

But Regional Edge location maintains a larger cache. Due to this the

object/content can stay for long time in Regional Edge location. Due to this

CloudFront does not have to go back to main webserver. When it does not find

any object in Global Edge location it just looks for in Regional Edge location.

This improves the performance for serving content to our users in Amazon

CloudFront.

https://aws.amazon.com/about-aws/whats-new/2016/11/announcing-regional-edge-caches-for-amazon-cloudfront/#:~:text=Regional%20Edge%20Caches%20have%20larger,improving%20overall%20performance%20for%20viewers.