HTTP vs HTTPS performance

Question

Are there any major differences in performance between http and https? I seem to recall reading that HTTPS can be a fifth as fast as HTTP. Is this valid with the current g

Answer 1

There seems to be a nasty edge case here: Ajax over congested wifi.

Ajax usually means that the KeepAlive has timed out after say 20 seconds. However, the wifi means that the (ideally fast) ajax connection has to make multiple round trips. Worse, the wifi often loses packets, and there are TCP retransmits. In this case, HTTPS performs really really badly!