It is claimed that ed25519 keys are better than RSA, in terms of security and performance. In terms of security, I understand that 4096 bits RSA keys are practically unbreakable for the foreseable future, so I am not asking about that.
What I would like to understand is the performance difference (in terms of speed). When people claim that ed25519 keys are faster, what does it mean? I am asking from the viewpoint of a user. I consider a couple of possibilities:
- It is faster to login into the server with ed25519 keys, but after that server-client communication is of the same speed.
- Initial login, and server-client communication, is faster with ed25519 keys.
- If you copy a file from/to the server, is the transfer speed any different?
- If I do ssh tunneling through the server, will I notice any speed differences?
Which is it? All of them? Neither of them?
So I am not asking about the mathematical differences between them, nor the algorithmic complexities to break their encryption, or the security guarantees. I am asking about the speed, in real world user applications.