> I tried to implement these recommendations but didn't seem to get > results I was expecting. How exactly does one reliably test that the > 1-RTT handshake is actually working?
Enable TFO and announce "http/1.1" via NPN and ALPN, that should do it. But your client will have to support all those features as-well (for example TFO can't possibly work in Windows). You will have to capture the TLS handshake in wireshark to see how fast it was (in terms of time and RTT's). Lukas