There's a very simple answer to this: Profile the performance of your web server to see what the performance penalty is for your particular situation. There are several tools out there to compare the performance of an HTTP vs HTTPS server (JMeter and Visual Studio come to mind) and they are quite easy to use.
No one can give you a meaningful answer without some information about the nature of your web site, hardware, software, and network configuration.
As others have said, there will be some level of overhead due to encryption, but it is highly dependent on:
- Hardware
- Server software
- Ratio of dynamic vs static content
- Client distance to server
- Typical session length
- Etc (my personal favorite)
- Caching behavior of clients
In my experience, servers that are heavy on dynamic content tend to be impacted less by HTTPS because the time spent encrypting (SSL-overhead) is insignificant compared to content generation time.
Servers that are heavy on serving a fairly small set of static pages that can easily be cached in memory suffer from a much higher overhead (in one case, throughput was havled on an "intranet").
Edit: One point that has been brought up by several others is that SSL handshaking is the major cost of HTTPS. That is correct, which is why "typical session length" and "caching behavior of clients" are important.
Many, very short sessions means that handshaking time will overwhelm any other performance factors. Longer sessions will mean the handshaking cost will be incurred at the start of the session, but subsequent requests will have relatively low overhead.
Client caching can be done at several steps, anywhere from a large-scale proxy server down to the individual browser cache. Generally HTTPS content will not be cached in a shared cache (though a few proxy servers can exploit a man-in-the-middle type behavior to achieve this). Many browsers cache HTTPS content for the current session and often times across sessions. The impact the not-caching or less caching means clients will retrieve the same content more frequently. This results in more requests and bandwidth to service the same number of users.
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Check your server software's configuration. It may be pointing port 443 (https) to a different default directory than port 80 (http). If so, you'll need to change the default directory for port 443 to match that of port 80.
If you're using Apache, I expect there are files named httpd.conf and ssl.conf somewhere, possibly in separate directories. (Most likely these directories will be at the same level or one will be a sub-directory of the other. Possible starting points are /etc/httpd/ and /usr/local/apache2/. These directories are usually named conf and conf.d.) Both files probably have entries for DocumentRoot (although the one in ssl.conf may be commented out with a "#"). If neither is commented out and they don't match, change the one in ssl.conf. See the Apache web site for more detail.
I've only used Apache, so I can't help with other servers.
And you probably know this, but I should mention it for completeness: Don't forget to make back up copies of your existing configuration files before you edit them! That way, if your changes don't work, you can go back to what you have.
Edit: I missed that this was Joomla, which I've never used. So, I'm not sure if this will be useful or not.
Best Answer
I believe the only place you really need to change is the configuration.php file. There must not remain a single one reference to BradPPresents.com
I have recently moved a Joomla site from one place to another and all it took was to fiddle with the configuration.php file for a while.