[jmull]

> The VDOM diffing made complex, fast moving UIs way easier to run performantly.

That was marketing more than reality.

VDOM diffing isn’t the slowest way to update complex UIs but it isn’t the fastest either. In practice your app often ends up generating a lot of VDOM which then gets diffed away… a bunch of work and then a bunch more work to determine the first bunch can be thrown away. The app developer needs to step in to manage and optimize the process.

[afavour]

Believe me, I know. We were manually diffing in a previous version before React came along and it was a shitshow.

The primary initial benefit with React was an improvement in reliability. Our previous implementation (in Backbone IIRC) wasn’t doing it quite right. Having it built into React was a gamechanger. Then with judicious use of shouldComponentUpdate you could minimize the amount of VDOM thrashing required.

I know at one point we explored immutable.js to make the diffing super efficient but the DX was pretty bad. I’m excited for JS to get records and tuples at some point and make that all way simpler. But for now it feels like shouldComponentUpdate and PureComponent are a lost art of React, few do it.