I don't understand your issues here. I built a community app for a hockey league that manages around 120,000 players in the DB. I do tons of loading, sorting and various algorithms on the data. I've never once had React be my bottleneck.

Rendering a page server-side and delivering it to users is about as inefficient a process as you can get unless you have massive resources dedicated to an optimization almost no one needs anymore. The virtual DOM is extremely efficient, it just needs more memory and CPU cycles on the client which are resources readily available. Browsers are very good at managing this in 2022.

Btw, your code in that article is completely irrelevant... I would not be showing people that article in 2022.