[SebastianKra]

Yeah, so you can't blame every performance issue you come across on a single topic, just because you've seen a YouTube video.

If you look at the performance graph, you'll see that most of the time is spent on recalculating css styles. Unfortunately, I can't drill into it because I'm not getting the same problems on my machine. Maybe it has something to do with the 1000s of rendered DOM nodes - no idea, but it has nothing to do with reactivity.

[CharlieDigital]

It's not because of the YT video; it's that the YT video provides a good walkthrough. I've been working with JS since the late 90's and have seen various front-end stacks come and go so to me, it is pretty obvious that React has this inverted nature and it is this inverted nature that is the root cause of why it's a very technical endeavor to get it to perform well at scale as it requires the engineer to think carefully about memoization and state placement -- something that doesn't happen in vanilla JS and early frameworks like KnockoutJS.