[hnlmorg]

The problem isn’t code size for unused cyphers. The very first part of any SSH or TLS handshake is agreeing to what cypher suit to communicate on.

The problem is purely the computational overhead of the encryption itself. This is why modern CPUs have instructions to offload some of that overhead to hardware.

You can think of this as the same kind of problem of MPEG encoding and decoding in software vs hardware. The difference in performance is massive. Then try to do that on a 40 year old 16 bit CPU with virtually no cache and only 1 MB of RAM to play with