> Less traffic and less latency per action: a single persistent connection avoids repeating the TCP handshake and the HTTP headers on every interaction.

You don’t need a TCP connection for everything.

If you’re optimizing for that you can consider client-side caching which you can instruct using cache headers that every browser support. That usually reduces heavy hitters by a lot, even if you set the browser TTL to 1 minute which is fine for most of the scenarios.