At the start of the pandemic, Eric made a strong case that all critical websites needed to rapidly optimise for high traffic and accessibility (here very much meaning both a11y and device/situation inclusion). I keep returning to it in my mind so wanted to note it here. Eric was specifically calling out sites for public health, government services, etc. – the social infrastructure that happens to live online – but it's universally relevant advice.
As much as you possibly can, get it down to static HTML and CSS and maybe a tiny bit of enhancing JS, and pare away every byte you can. Because too many sites are already crashing because their CMSes can’t keep up with the traffic surges. And too many sites are using dynamic frameworks that drain mobile batteries and shut out people with older browsers. That’s annoying and counter-productive in the best of times, but right now, it’s unacceptable.