[simjnd]

I want to preface this by saying I have nothing against React, I have used it professionally for a couple years and it's fine and perfectly good enough.

That being said React is slow. That is why you need useTransition, which is essentially manual scheduling (letting React know some state update isn't very important so it can prioritise other things) which you don't need to do in other frameworks.

useOptimistic does not improve performance, but perceived performance. It lets you show a placeholder of a value while waiting for the real computation to happen. Which is good, you want to improve perceived performance and make interactions feel instant. But it technically does not improve React's performance.