what is PDO?

many clients ask me why I suggest to use PDO as part of optimization

it is very simple
PDO structures is native PHP drivers, which mean that was designed and optimized for PHP

Just image, libmysql use buffers and PHP interface use buffers. This mean that functionality is doubled! It is absolutely normal step to remove libmysql as layer. As part of server optimization this step require MySQL 4.1 as minimal version.

At the end, migration from libmysql usage to PDO save up to 40% server resources!