[dounan]

First off, thanks for your work on React! Makes all of our lives easier as developers :)

As dmnd pointed out, I'm not entirely convinced that dropping PureComponent everywhere is not a good idea.

For our app specifically, we unfortunately do data loading in a lot of places, which means that there are quite a bit more than just few places that can benefit from being a PureComponent. Our current idea is to try to make everything a PureComponent, and go back and 'unpurify' the places that have wasteful sCU comparisons. This might not turn out to be a good idea though, for the reasons you mentioned.

I'll make sure to do some profiling in our codebase once we get to that point, and see how much wasted sCU we are doing.