I'm developing a series of scripts containing common interfaces for certain tasks, such as a user-login, so that any page that requires a particular functionality can require() the appropriate files. So far I have been piling all the functions for a given task-set into one source file. The largest of these files is ~6kb in size, and could potentially double in size (or more) before I am done. (That is, 6kb of php source only.)
Essentially, I am wondering at what point will the file size start to bog down the PHP parser. Given that for each page served which includes a source file, the entire thing will be processed by the PHP parser before any source code is executed, I am concerned about slow load times, as well as grinding the cpu to a halt.
All this, of course, is speculation at this point. It may be that I am optimizing prematurely. However, I would appreciate feedback from anyone who has had an experience with a situation similar to mine.