Some unknown guy (ok, he is famous for writing the fantastic Flysystem) has written an insightful post on his new blog on how and why to render ReactJS templates on the server.

Rendering your templates server-side has some obvious benefits. Since the contents of the page is there in the initial response, there's less page build-up. This will give your application a more snappy feel to it. It also ensures your pages can be correctly indexed by search engines. An additional bonus is presented in the way that React handles your pre-rendered page.

When React templates are rendered server side, a checksum is added. This hash is checked by the front-end ensuring the UI is in the correct state, and if so, that representation of the DOM is accepted, preventing any further rendering on the client. This, once again, creates a smoother experience in terms of performance.