You have just looked at improving the efficiency of your
PHP applications by using features of the PHP language to your advantage.
Of these, you can probably get the most significant improvement
through careful selection of the most appropriate built-in function for
the task at hand. In fact, this idea alone constitutes nearly half of this
section. You can use the other techniques discussed to further tune your
applications for best performance.
In Optimizing database queries, let's look at improving the performance of
your SQL code when used within your PHP applications.