[shermanmccoy]

It's more overhead in the sense that mobx needs to walk all your store objects and check for changes, on top of what React does. Anyway that's fine if you really need that precision. I just useMemo at the 'hotspots' and that is enough. Remember also that if vdom diffing doesn't pick up a change, nothing is flushed out to the DOM, so whether an object is created or long-life doesn't matter in this sense.

[cloverich]

> mobx needs to walk all your store objects and check for changes, on top of what React does.

I don't think that is quite correct. I think it keeps a mapping of observed properties and which React components rely on them. Then, changing any property becomes a lookup (not a walk) of who is observering, and a `forceRender` on the results. So if no components are observing the property, there's no further computation. Its not "on top of what React does" because it short-circuits it (like useMemo) -- except you don't have to hand-craft any useMemo comparators, it does that for you by tracking which properties you access.