“Most” react apps needing “seconds” definitely needs some citation or evidence. Even in fairly heavy and laggy react apps, it’s still usually network latency, waterfall requests, ad/tracking bloatware, large asset sizes, and the usual old classics that cause perceptible slowness in my experience.

In my humble (backender) opinion, if it's hard to use a tool right, that counts as a cons, and that must be accounted for when choosing which tool to use.

You probably never see what reddit like after it just get rewrite. https://www.reddit.com/r/bugs/comments/rj0u77/reddit_redesig...

I won't say most react apps performs like this. But it's what you will get if you ship a big react app without optimization at all.

Other framework mostly have a much saner default (for example, component without argument change does not re-render). So it will work well (not best though) even in large scale. But in react they are all opt-in.