On Tue, Aug 28, 2012 at 4:39 AM, Matijn Woudt <tijnema@xxxxxxxxx> wrote: > First of all, I believe [A] PHP is smart enough to not generate bytecode > for functions that are not used in the current file. Think about the > fact that you can write a function with errors, which will run fine > until you call the function. [B] (except for syntax errors). [B] negates [A]. PHP must either parse the file into opcodes or load them from APC and further execute the top-level opcodes. That means defining functions (not calling them unless called directly), constants, global variables, classes, etc. No amount of measuring is required to tell me that doing X vs. not doing X in this case clearly takes longer. Now, is that time significant enough to warrant the extra logic required? In my case, absolutely. We organize our library into many classes in multiple files. By using an autoloader, we simply don't need to think about it. Include bootstrap.php which sets up the autoloader and include paths. Done. In the case with a single 50k library file that is used on 10% of the pages, I'd absolutely require_once it only in the pages that need it without measuring the performance. It's so trivial to maintain that single include in individual pages that the gain on 90% of the pages is not worth delving deeper. Peace, David
