Doesn't matter much: you do not send it over he Net anyway. As you like. Usually they are kept reasonably long for reaing and editing them to be easier, breaking a script in a bunch of includes. In case you do conditional includes instead of keeping all the code in one file you also should experience some speed improvement, since only the executing code gets parsed (as I understand). On the other hand, includes mean disk reading, which is rather slow operation. Anyway, you can't notice the difference until you run smth as popular as yahoo or google, so don't mind.