[Jasp3r]

I wouldn't call reactivity in Vue "fine grained". Every object that gets loaded into component state becomes reactive, and every piece of code that touches it gets dragged into a massive internal dependency tree.

Vue has blacklisted reactivity, everything becomes reactive (and observed) by default and you can opt-out, while MobX features whitelisted reactivity and is much more fine-grained

[rk06]

I say fine grained as changes in an object will invalidate only that object, and only it's dependencies will be updated.

Contrast with coarse grained reactivity I. E. angular, where it must dirty check all "reactive" objects to identify the changed object. As angular can't tell exactly which properties changed.