The CPU intensive part of a HTTPS connection is the initial key negotiation/session setup (using asymmetric encryption methods). The symmetric encryption of th

The CPU intensive part of a HTTPS connection is the initial key negotiation/session setup (using asymmetric encryption methods). The symmetric encryption of the actual traffic is pretty trivial. You can amortise the session setup cost by ensuring the HTTPS session caching is enabled on your server (in Apache, the directive is SSLSessionCache). This will let subsequent connections from the same client re-use the same SSL session.