Frontend

Mark Erikson (Redux maintaiiner) provides us with "details on how React rendering behaves, and how use of Context and React-Redux affect rendering". Must-read for every React dev!
Facebook has finally released its own state management library. It's still experimental, but it's definitely worth a try. Given that it comes from the same company, it's reasonable to expect that it plays nice with the upcoming concurrent mode, suspense, and anything else we don't know of yet.
A great read from Harry Roberts on how to make your font render faster than ever.

Node.js

In our view, it's the most comprehensive yet not bloated guide on how the event loop works. An absolute must-read for every Node.js developer!
Have you ever wondered how V8 manages its memory? Here is a concise overview with great visuals.

A long-read coming in 9 parts on what every programmer should know about the memory. It is 13 years old, but it is as relevant today as it was back then.
Async context propagation is a pain in the ass in any eco-system. Google provided us with an outstanding comparison of how different languages and frameworks approach it.
A new episode of a never-ending battle between Kyle Kingsbury (author of a well-known Jepsen) and MongoDB. He evaluated MongoDB version 4.2.6, and found that even at the strongest levels of read and write concern, it failed to preserve snapshot isolation. MongoDB promises a patch in 4.2.8.
Everybody knows B-trees, right? But what about other ways to speed up your search? Marko Kevac from Badoo speaks about their usage of bitmap indexes.

Did you know that it's simple enough to build a time series storage on top of RocksDB which is capable of writing 400K data points/sec on decent HW? And yes, it uses bitmaps. Andrey P, who is a big fan of time series (and bitmaps), recently did a talk on the topic.