Realistically, a server-side rendered JS app is also going to run most of the code that runs in the client per page load, so you would also have to consider initialization costs as well. I've had to work on one that took 100+ ms to render a static page (without accounting for network latency), which a static file server could render the same page orders of magnitude faster.
Long story short, most of the newer, non-string based JS server-side rendering does not consider performance a factor and consequently, perform pretty terribly. There are band-aid fixes such as putting a reverse proxy in front or running on super fast hardware, but it's like putting a band-aid on a bullet wound.
[0] https://github.com/daliwali/simulacra/blob/master/benchmark/...