Comment by machty

There are heuristics to prevent recursing into obviously-removed/added elements (using component type and keys), but aside from that, there's always going to be a tradeoff between frameworks/libs that choose to track this granular information to know exactly where a change originated and what needs to be updated, vs libraries like React that don't set up any sort of observers or have any sort of knowledge about where the change originated from, and React has demonstrated that their approach is pretty fast due to the fact that live mutable DOM manipulation is the bottleneck and not purely JavaScript traversals.