Ever since my move to a VPS, one of the drawbacks is that mod_php uses a lot of memory since Apache has to load the PHP stuff every time a page loads. This can be solved by switching to PHP5-FPM and Fast CGI, which gives the performance of Mod_PHP without the high memory usage.
What is PHP5-FPM? It’s a separate process on FastCGI and separately from the web server. It’s commonly used with Nginx, but I decided against using that server since it would cause a configuration nightmare, especially since my .htaccess files only works with Apache.