It is unrelated to SSH, it is a generic TCP thing.
"hello world" fits in a single TCP packet, but the kernel might end up sending one packet containing "hello" and another packet containing " world". It is completely opaque to userspace.
TCP_CORK lets userspace decide when packets are dispatched. You get to control whether "hello world" is sent across 1 packet or 11 packets.
I’m aware what TCP_CORK does. I’m not seeing how it helps the situation in the post.
Ah, maybe you are saying it doesn’t help the situation in the post. That’s what I misunderstood.