In 2018, does SSR still provide an advantage over CSR for: (1) SEO, (2) performance?

I have read a number of articles singing praises for one or the other. SEO and performance are the two greatest weapons that SSR seems to wield over CSR. However it seems that in 2018 most search providers have crawlers capable of parsing JS and some async calls (up to 10s for Google). And with frameworks like Preact being tiny, especially when gzipped, I don't really buy the performance argument either. Has anyone come across a definitive, recent writeup that compares the SEO and rendering performance of SSR and CSR?

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Nico Hoogervorst's photo

SEO

Test your CSR with 'fetch as bingbot', 'fetch as googlebot' .

Yandex (duckduckgo) currently doesn't run javascript.

Performance

It depends. In some countries you might only get a 2G connection. Camping sites have terrible flaky wifi. Both download size and latency becomes an issue. CSR takes time to load and run JS, but once running, an CSR app can react snappier (optimistic UI).

If the requirement is: offline-first app, then CSR is the only option.

Accessibility

CSR/SSR can be made accessible (WCAG 2.0), but it takes effort. Test your pages with Apple VoiceOver and NVDA. A screen reader reads from the browsers DOM tree, so javascript doesn't have to be an obstacle.