Most of us hope that any site we build will be successful, but rarely do people actually plan for success. As traffic starts to increase on your site, however, you will need to at least put some thought into how you plan on scaling your Joomla deployment to fit your needs.
We could easily write an entire book about scaling and performance tuning any PHP application, but in this Short Cut we only have time to give you a few things to look into.
PHP Distributions: although you can always build PHP yourself or use the distribution that may come with your server, you can certainly use a pre-build distribution. We mentioned early in the book to use an XAMP distribution as you read, but for production you will probably want something a bit more tailored to your needs.
Windows and Linux: we recommend Zend Core (http://www.zend.com/en/products/core/).
Mac OS X: just use the PHP distribution that comes with operating system. If you have a Mac OS X 10.3 or 10.4, then we recommend the Entropy builds from Marc Liyanage (http://www.entropy.ch/software/macosx/php/).
Caching and Acceleration Systems: in short, these systems will cache generated PHP pages, which allows the overall system to be faster—it will serve pages out of its cache versus having to hit the database again.
Alternative PHP Cache (APC): http://us.php.net/apc
memcached: http://www.danga.com/memcached/
eAccelerator: http://eaccelerator.net/
XCache: http://xcache.lighttpd.net/
Full PHP Platforms: if you are running a full-blown commercial site and you have multiple servers, need easy management, monitoring, and reporting tools, then the Zend Platform (http://www.zend.com/en/products/platform/) is where you want to go.