Pervasive end-to-end encryption is the only way to defeat deep packet inspection-based spying, throttling, and censorship, which is increasingly popular among governments and ISPs (and even end users e.g. Firesheep). The overhead of encryption is actually tiny, contrary to common perception. It should never be optional.
that is not 100% true, you are always going to pay at least 1 extra round trip up front for an encrypted connection, for NY-Sydney latency this would wack on 250ms extra to the first request, http keep alive mitigates a bit.
Encrypted protocols can prearranged a session key and/or initialization vector to use for the next connection, dramatically reducing the start up delay.
