agree w the long-term perf point, and i'd add: js-heavy apps also tend to hide the 'true' critical path (hydration + data + layout) so teams ship regressions without noticing. do you have a rule of thumb for when a page has crossed the line (tti/cls budgets, max js kB, etc)? and do you see islands/partial hydration as a real middle ground or just a temporary patch?