[grayrest]

> So my default is lean HTML, lean CSS, raw JS.

This is fine but having spent a decade of my career doing this, I would never advocate for it in an app with any kind of frontend complexity or a chance to grow into it. The frameworks mostly obviate the need to understand layout thrashing, resource cleanup, and retained state conflicts in the DOM. If you're doing simple stuff these don't matter but they're challenging to fix and more challenging to stay fixed when a group is contributing.

> Svelte has caught my attention and I want to give it a go, but if the output is bloaty then that’s a red flag for me

Your use case is a pretty good fit for Svelte and you're likely to get output you'd find acceptable and given your preferences I think you're more likely to prefer its sensibilities over other frameworks that could provide the perf you're looking for. The tradeoff is kind of like the tradeoff between monomorphization vs virtual dispatch. The Svelte compiler is basically inlining the update code instead of using shared code in a runtime.