

JS is fine, it’s more that people overdo it and bundle their heavy, deeply layered frameworks with thousands of npm dependencies for the web. Often times analytics/tracking/ad libraries are a major contributor of bloat, I once shrunk down a package-lock from thousands of lines to a few hundred just by stripping the telemetry libraries from an open-source app.
Use the right tool for the job. Sometimes it’s a static page, sometimes a server-rendered dynamic page and sometimes a single-page application, all of those can be made performant.
A good reason to pick GPL is if you want to allow GPL software to integrate yours and you don’t care that much about the AGPL clauses (e.g. because your app isn’t a server).
CC0 might be a good fit for trivial template repos where you don’t want to burden downstream projects with having to include copyright notices.