The biggest performance problem that a CDN solves is the latency issue. Latency is the amount of time the host server takes to respond to the page request of a visitor for content on a website.
CDN directs a visitor to the server closest to them. Servers closest to the visitor's location have the least issues of latency. People requesting for page content from far away locations will experience slower server response mainly due to the distance and number of devices the content passes through before it reaches its destination. A CDN caches static content in distributed servers via edge caches, POPs across a region and brings the content closer to a visitor.
Cloud Delivery Network (CDN) works on the principle of duplicating and distributing content across servers that are placed at multiple locations. When you use CDN for your websites you can choose the servers that are closest to your target audience. CDN also addresses the bandwidth costs. It also ensures 100% availability by distributing traffic load from a server to the closest idle server within its network.