[tombrossman]

> I think op is saying, at the cost of an undetectable fraction of a second rounding error when you SSH somewhere, so what?

I tried switching from a 2048-bit to a 4096-bit key to control a modestly sized VPS (~4GB RAM, 2CPU) and scp file transfer speeds plummeted.

I have a symmetric 1GB FTTH connection and I'm used to everything being pretty quick. Using a longer key was like a return to dial-up speed. If you don't plan to transfer large files or directories you can safely ignore it, but I bet your patience will run out pretty quickly if you do.

[fulafel]

The public key operations are only at the start of a SSH session, there isn't any effect on the transfer speed aside from the initial setup time.

(Unless you are saying you somehow convinced SSH to use a symmetric cipher with a 2-4k key size...?)