How would performance be a concern for rendering the UI of a terminal app? Surely that happens in less than 0.001% of all cases. And of course no one in their right mind is implementing the core functionality of their app with react state variables. (Right..?)
Haven’t used this library, but the answer is the same as it is for real React apps. How does this application perform if I have a scrollable view with 50,000 items in it and I press the down arrow? This kind of thing is why React can be the cause of bad performance.
Any viewer of data that has 50,000 elements in it has this many items with a scroll wheel. It doesn't matter if it's on the screen at the same time, this is the kind of thing that the UI is supposed to be abstracting away from you; you just describe the UI and the renderer makes it appear on the screen. Example apps (not built with Ink, just some that fit into this category): less, https://fx.wtf, sqlite...
And this is why React apps end up with bad performance by default. Doesn't crop up in simple tests and light usage, but the bad scaling will catch up with you when you deploy to production.