React only "renders" everything within its shadow DOM. It then applies the results of diffing the previous and current version trying to use the most atomic operation (innerText, add/removeClass, add/removeNode, etc)
Say you want a form with as-you-type validation. You can't have a view containing the whole form and just re-render that as someone types. If you did, you'd lose the user current focus on every render. This forces you to manipulate parts of the DOM "by hand", something React abstracts for you.
I find Backbone events extremely hard to work with (error-prone, super hard to test / debug), because there are many operations that emit tons of events. So you either listen+render() on any event (very inconsistent performance if your app has any kind of complexity), or you hand-pick the events you want to react to (event-hell). Using immutable objects along with React's PureRenderMixin means you can just render() on any change, with great performance. It makes your UI purely functional, very easy to reason about, and easy to test.
Same experience here. I took 0.1g to close to 1g on several occasions over a couple years.
Doses in the 0.1-0.2g range would leave me fairly slow the next day, but that's it. With heavier doses I'd see after-effects for about a week (like reaching for my phone and pulling a lighter from my pocket, disconnecting in the middle of a conversation, losing track of time)
The only time it took a long time to fully recover (5-6 weeks, progressively) was after taking some twice in 2 consecutive days. Quantities weren't big, maybe 0.5g total, but the effects lasted really long.