The problem is that they don't work to fix performance issues unless they're implemented all the way up the tree. So if you have a perf-sensitive view, then you

The problem is that they don't work to fix performance issues unless they're implemented all the way up the tree. So if you have a perf-sensitive view, then you'd better hope that your "application frame" components (or anything higher than the perf-sensitive component in the tree) are optimised to avoid re-renders. And it's a massive pain to retrofit this in later if you haven't been strict with it from the start.