Recommended CDN: MaxCDN
Files are kept on servers all over the world to speed up the time it takes to deliver content to your browser. CDN’s are efficient because the likelihood of them being closer to your location is greater. This is because there is more than one place that your data is stored.
Your hosting provider will likely have a few datacenters, but chances are that your data is only stored on one of them. CDN’s keep your data on all their servers.
The main benefit of a CDN is it takes care of all the heavy lifting. With certain files only being pulled from the CDN and others being pulled from your hosting companies servers, you have two places to retrieve files.
Instead of having to wait for all files from one place, a CDN makes it possible to pull from multiple servers simultaneously. This is where a lot of the efficiency and speed are gained.
We use them on all our sites. The bigger the site, the more likely it needs help carrying the load of data. Unless you are on a dedicated server, you should get a CDN. Of course, a CDN is part of the whole, “Speeding Up” process. If your site will still be slow because of your hosting provider, or too much information per page, there may be other factors to look at first besides a CDN. Head back to our Ultimate WordPress Performance Guide and see what other steps you can take to speed up your site.