I was really asking what "IPC" means in this context. If you can just share a mapping, yes it's going to be quite fast. If you need to wait for approval to come back, it's going to take more time. If you can't share a memory segment, even more time.

No idea what this vibe code is doing, but two processes on the same machine can always share a mapping, though maybe your PL of choice is incapable. There aren’t many libraries that make it easy either. If it’s not two processes on the same machine I wouldn’t really call it IPC.

Of course a round trip will take more time, but it’s not meaningfully different from two one-way transfers. You can just multiply the numbers I said by two. Generally it’s better to organize a system as a pipeline if you can though, rather than ping ponging cache lines back and forth doing a bunch of RPC.