HTTPS is slower

[rackaid]

HTTPs is slower due to the cpu overhead of SSL. The only way to know for your application is to do some benchmarking using something like apache bench (linux, there are windows tools as well).

Also do not use HTTPs unless you need to. HTTPS does nothing for server security -- only content security. In fact, running Apache with mod_ssl is less secure than running Apache without it due to the number of mod_ssl exploits that appear.