One long class or many shorter classes?

Question

In PHP, is there any performance impact on using one long class with a lot of functions in it? Or is it advisable to use many small classes and call them separately when needed?

Answer 1

Personally for me I would much prefer to break the classes down into smaller files based on what they are for. If that's business objects then having a 'customer.class.php' 'account.class.php' etc would be my preference.

In most of the projects on which I've worked it's been like this, then a larger 'lib' or 'common' file which includes lots of various functions which are used all over the place.