Back in 2010 we went through exercise of first using a local data center and then using a CDN in a different country.

Interestingly enough using a remote CDN had much smaller latency. After doing an in depth analysis this is what we discovered.

There are two factors that influence your latency: throughput of the pipe and speed of the physical server.

Let's start with throughput. Consider two scenarios. In the first one you're using CloudFront from Amazon (or any other big name CDN) which probably has direct connection (or near direct) to the continents fiberoptic pipe.

The second scenario is if you build a data center in the country. In this case you will be removed from the main pipe by several hops through internet providers which in turn will narrow the throughput after every hop. Unless you are willing to pay very expensive bill for the access to continents, or at least contries main pipe the latency will be higher than from big name CDN's.

The second aspect deals with the type of servers involved in servicing GET requests. You need to install top notch hardware with very speedy SSD hard drives and extremely fast networking cards. You can go as far as start optimizing bus speeds between the components. All that leads to increase in price per server.

If you're using a CDN then you're much better off because all of that is taken care of for you and you constantly run on latest and greatest hardware that you don't need to upgrade. Count in the amount of time/money need to be spend to service a data center. From my experience the companies that do administration on demand are slow for near 100% uptime requirements so you will need to hire and staff to do monitoring and maintenance.

Also never forget about redundancy that also needs to be provided as your server will fail and will go down. Security is also a concern.

My conclusion from the the evaluation done in 2010, which is much stronger today, go with CDN unless you're a Fortune-500 company and need a dedicated special use data center.

Current CDN's usially offer multiple data centers at different continents for your disposal that can further shrink your response time.

Good luck!
Denis.