It is said that using immutable data is better in performance and effective in Reactjs based code/apps instead of dealing with mutating data for changes.
So a typical re-render check over data in ReactJS seems to be a comparison of states, current and previous of the specific React component. This check works a lot faster with immutable data since its needed to compare just the state objects eventually.
To make your data flow and app flow more efficient, Reactjs provides with helper functions that you can help yourself to code in immutable data. Here is more on the helper functions: https://facebook.github.io/react/docs/update.html