initial rendering should definitely be on the server, his premise to render content on the server side and then async load it in is flawed, he adds latency and the dom still has to parse a string at the end of the day and put them on the display tree, so the only bit he offloaded was a bunch of string concatenation (given he used a sane templating system) at the cost of latency. bad trade off IMO.

the downside to his reasoning is that he is tying himself to a single back end (node) if he used something like mustache he coulkd use any backend, but mustache implies parsing templates on the client. googles closure compiles to javascript functions and I am sure something like that exists for mustache and this would seem very sensical.

Converting a large string to a dom element is not expensive, it is when that dom element is added to the actual display tree when things go a bit awol, this is to be expected, redrawing any GUI costs a lot.

React is an excellent library and I am glad people use it, none of the ideas are radical however.