Just tested again. Performance is good when idling, but while loading content in a heavy channel, scrolling gets laggy and one CPU plateaus for a while. Maybe the app is inserting DOM nodes individually, in a loop?

I guess it's too early for me to evaluate the performance of Twist, because I am not on any large teams there. But I can see that Slack at least, has room for improvement in rendering performance. Perhaps there is some general optimization they are missing out on, like immutable state + shouldComponentUpdate. That one saved a flailing app of mine in the past.

I'm in Firefox on Linux, i7-4500U, 8GB ram.