Thanks, I am more interested in developing social websites with modern look and more performance, I mean like the design of medium.com or hashnode.com, I think

Thanks, I am more interested in developing social websites with modern look and more performance, I mean like the design of medium.com or hashnode.com, I think they do render the first page fully canonical HTML, and then every subsequent request is rendered using the js framework GETing some JSON which gives more space to the server to do other work. I am really interested in this approach but I fear about the SEO and any additional unnecessary complexities like compatibility with old browsers and OSs especially in Android.