[jimrandomh]

I think Material UI (and the whole ecosystem of Javascript libraries of which it's a part) are drastically underestimating the costs that churn imposes on their users. I say this as a developer of a codebase currently on material-UI v3, looking at v4 and v5, having bounced off the task of upgrading a few times and currently thinking it's probably not worth it.

Material-UI v3 had an issue (which I think v4 and v5 probably still have?) where CSS-in-JS winds up retranslating Javascript blocks into CSS and adding them to every SSR, and then retranslating them again on the client as part of the pageload, which wasn't performant enough for us. So we set up a system where we would pregenerate a static stylesheet with deterministic names, and serve that as a cacheable resource. Then v4 comes along and all of the CSS-in-JS related wiring is different, so our static stylesheet thing would have to be rewritten, and then v5 comes along and it's been redone again, and it doesn't look like I want to touch this without some signal that it's stabilized.