- Use the React DevTools Profiler to identify components that are rendering more than expected, or taking too long to render

- Wrap key components in `React.memo()` to have React avoid recursing through those subtrees unless the component props have actually changed

- Avoid putting large state objects into a single context provider, as all components reading that context will re-render whenever it changes (and all of their children too)

- Use `useMemo` to cache any expensive transformations that happen during rendering

I've got an extensive post that covers how rendering works as a whole, and has a section on understanding React perf optimizations:

- https://blog.isquaredsoftware.com/2020/05/blogged-answers-a-...