@thor plain HTML, CSS and JS are gentle, but have you looked at the fuckery required to do anything with the framework stuff which is the "state of the art" today? that is outright unhealthy.
depending on the supporting libraries (UI toolkits) i'd rather write web apps in e.g. Go, yes. there are actually toolkits for Go which can be compiled to WASM: https://gioui.org it's not _fast_ but i'd say that's very likely due to the assorted cruft in browsers.