content: if someone hijacks your session in a man-in-the-middle attack then you may never ever be able to get out of it.  Fortunately cryptographers don't actually make decisions based on utterly flawed logic like this. You don't gimp the performance of your protocol because "at least if it gets hacked the inefficiency will slow them down". You design it to be as secure as possible and if it's somehow broken, all bets are off. If you take your logic to extremes, it basically becomes:  Hey guys, let's limit the protocol to 1 byte per minute to slow down hackers after they crack our ROT13 encryption. And let's make sure to waste round trips renegotiating sessions, just in case the hackers didn't get everything they wanted in the first session.