No. This is exactly the same. Think about life of a data gram or stream bytes on the syscall edge for each.

I’m not sure I understand. This isn’t something I haven’t thought about in a while, but it’s pretty intuitive to me that a loopback TCP connection would pretty much always be slower: each transmission unit goes through the entire TCP stack, feeds into the TCP state machine, etc. Thats more time spent in the kernel.

Yea but those aren’t context switches.