Caddy 2.11's default post-quantum key exchange sends six times more handshake bytes

Caddy 2.11.4 enables the hybrid X25519MLKEM768 group by default for post-quantum key exchange in TLS 1.3. Measurements showed handshake volume grew 6.1 times (from 440 to 2704 bytes), while CPU load remains below 65 microseconds per operation, and old clients without ML-KEM support connect without errors.

• ClientHello grew from 318 to 1494 bytes, ServerHello from 122 to 1210 bytes
• ML-KEM-768: encapsulation over twice as fast as X25519, all operations <65 µs
• OpenSSL 1.1.1f from 2020 completes TLS 1.3 handshake without errors
• Caddy does not log the selected key exchange group in JSON logs