Amen to that. Half the reason I like this site is it loads instantly. Not showing spinning wheels just to display some text.
As for "working at scale", this post itself is id ~35 million. You could likely fit all of that into ram on a modestly sized server.
It's idiotic complaint really. I switched from Go templates to pre-compiled ones because of engineering wankery of personal project where I wanted to have page render take less than 1ms, and with templates it took like 3-4ms. Even with something complex at say 50ms per page you're looking at ~200req/sec/core which is a lot of traffic
It will most likely be fast enough. If not there are libs that will compile your templates to Go code with very minimal overhead, or templating libraries that are much faster than builtin one.
I'd think adding megabytes of JS garbage just to run site would be opposite of "HN clone"