One way to improve cpu-bound performance is to switch to something like HipHop for PHP [1], which compiles PHP down to C++ and runs that. Granted, this incurs a non-trivial switching cost.
However, it's scary to me that someone is suggesting the potentially fatal-inducing use of "require" over "require_once" (if you call it twice on the same file, you end up re-defining whatever classes or methods were required and the script dies). It seems like optimizing for developer time and simplicity over cpu utilization is better here. Using HipHop would incur a one-time operational cost, but I suspect it would be worth the additional developer and speed gains.
By using __autoload and a class/file naming convention, you can get away with using just require, and not having to write require statements manually. Decreased time for developers, and near optimal load times.
However, it's scary to me that someone is suggesting the potentially fatal-inducing use of "require" over "require_once" (if you call it twice on the same file, you end up re-defining whatever classes or methods were required and the script dies). It seems like optimizing for developer time and simplicity over cpu utilization is better here. Using HipHop would incur a one-time operational cost, but I suspect it would be worth the additional developer and speed gains.
[1]: https://github.com/facebook/hiphop-php/wiki/