If size does matter...do you think removing the ASCII from each and every file in src will reduce lag? PMMP is around 3MB. Removing ASCII art from every file might get it down to 2.5 or less...!
No. Not at all. For compile time: for each file it might spend an extremely negligible amount of time for disk I/O reading the comments. Since this is only done on server startup, it has nothing to do with lag at all, since lag is about runtime. For runtime: the license header comments are not stored into memory. In runtime, PHP does not read the source files anymore. PHP will just use the in-memory compile code it created during compile time.