If there is some slow component where it is worth spending time to do special optimizations, you can use an equality check - or some component-specific check; b

If there is some slow component where it is worth spending time to do special optimizations, you can use an equality check - or some component-specific check; but my point is that using Immutable and PureRenderMixin by default will speed up lots of situations without having to do any extra work. Moreover, using Immutable is also much less error-prone.