PHP Dynamic Web programming: include () vs. require ()

PHP's require () performance is similar to include ().

The difference is that, for include (), files are read and evaluated every time the include () is executed, whereas for require () the file is processed only once (in fact, the contents of the file replace the require () statement).

This means that if you have code that contains one of these directives and code that is likely to execute multiple times, then using require () is a high efficiency. On the other hand, use include if you are reading different files each time you execute your code, or if you have a loop over a set of file iterations, because you can set a variable for the file name you want to include, and use that variable when the parameter is included ().