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