Why not use HTTPS for everything?

Question

If I was setting up a server, and had the SSL certificate(s), why wouldn\'t I use HTTPS for the entire site instead of just for purchases/logins? I would think it would make

Answer 1

https requires the server to encrypt and decrypt client requests and responses. The performance impact will add up if the server is serving lots of clients. That's why most current implementations of https is limited to password authentication only. But with increasing computing power this may change, after all Gmail is using SSL for the entire site.