> My (probably naive) understanding is that 25519 already provided better performance than other algorithms used for similar purposes (e.g. RSA) when tuned for a roughly similar level of security; anecdotally, generating 2048-bit or larger RSA keys for me tends to be a lot slower than ed25519.
My also naive (an possibly out of date) understanding is key generation is much faster in with ecc, and that signing is faster too, but verifying is faster for rsa. So switching from a RSA to an ECC server certificate saves bytes on the wire, because keys are smaller, and saves server cpu because signing is faster, but may increase client cpu because verification is slower. The byte savings may make up for the increase in cpu though.
> My also naive (an possibly out of date) understanding is key generation is much faster in with ecc, and that signing is faster too, but verifying is faster for rsa. So switching from a RSA to an ECC server certificate saves bytes on the wire, because keys are smaller, and saves server cpu because signing is faster, but may increase client cpu because verification is slower. The byte savings may make up for the increase in cpu though.
Interesting! I wonder if this new algorithm is intended to help with that. I'm super curious if the smaller payload does indeed make a difference (with the current algorithm) like you mention; I know that with databases and filesystems, compression is commonly used to shift the balance from I/O to CPU due to disk writes being slow (with reduced storage size being a side benefit but not usually the main motivation), but I also know that cryptographic verification being too slow can be an anti-feature if it makes brute forcing feasible, so the amount of CPU work needed might be pretty high still.
It's 11 k verify/s for ecda vs 39k verify/s for rsa-2048. A TLS handshake needs at least one sign and verify from the server cert, plus some verifies for the signature on the cert chain (but those signatures are used over and over).
My also naive (an possibly out of date) understanding is key generation is much faster in with ecc, and that signing is faster too, but verifying is faster for rsa. So switching from a RSA to an ECC server certificate saves bytes on the wire, because keys are smaller, and saves server cpu because signing is faster, but may increase client cpu because verification is slower. The byte savings may make up for the increase in cpu though.