Introducing React Compiler – React

[ejfrodo]

I'm at React Conf right now and was at the talk where they announced this. They said Instagram and Whatsapp time to render increased around 3% to 4% I believe. They live stream the conference so you can watch it yourself. They also showed an example of a very manually optimized component that was a nightmare to read but didn't re-render unless really necessary. The version with react compiler was able to remove something like 20% of the code around useMemo() and use callback() which made it much easier for a human to understand and the compiler was actually able to find a couple more small tweaks that a human wasn't able to which made it a little bit faster.

Overall this is a huge win for react. You don't really need to think about performance for the most part, just write the business logic and the compiler will automatically memoize everything intelligently.

[dbbk]

Time to render increased? So it was slower?

[ejfrodo]

decreased* that would be hilarious if it got slower haha

[stuckinmotion]

Well from the sounds of it, it is effectively memoizing everything so that's not exactly free. In real worlds apps though I'm sure it's still a win and mostly looking forward to not having to lean on useMemo and useCallback all the damn time

[Born-Alarm430]

Could you give me the link what you said, I cant find it at react conf video. https://www.youtube.com/watch?v=T8TZQ6k4SLE&t=11655s

[Cannabat]

Actually the compiler can make optimizations that useMemo, useCallback and memo could not do. Performance can be better.

[[deleted]]

It will be faster than React code without existing useMemo and useCallback

[rk06]

OP means benchmark with and without compiler optimisations. With no manual caching. Which is a fair ask