Cloudflare provides a free CDN plan. Here is my personal experience on why we should not use cloudflare free plan for all the websites.
I have used the cloudflare free CDN for a while for one of my website developed in ASP.NET MVC. The main purpose of using the CDN is to serve static content of the website quickly based on your geographical location.
How a CDN works?
When it is recommended?
So in my case, cloudflare did not help to increase performance but increased server lookup time. This could be because of multiple server lookups in between you and your web server(server on which your code resides).
Note: My hosting server is located in USA and I used to open my website from India.
This is purely my personal experience and my observations on usage of cloudflare’s free CDN plan. It could be a different case for you. So consider all the scenarios before using the free plan. If you had a different experience then please comment.