Client-side CPU usage, as well as page weight, isn't a problem if JS is done right. Angular-like bloatware certainly ruins all the zen. But that doesn't mean you should rush to another margin and make everything server-side. Modern web technologies allow you to keep everything beautiful, smooth AND lightweight. But in order to achieve that, you'll need to learn more than a couple of bloatware libs like angular or jquery. In fact, you need to forget them and start thinking for real. And study, study and once more study MDN manuals.

Language doesn't make Web slow and bulky. People do.