Add $config->prependTemplateFile and $config->appendTemplateFile options, which allow you to specify a PHP file to load before and/or after the main template of a given page. For instance, you might have a common init.php that sets up some shared functions. Or you might have a common output file automatically loaded afterwards, etc.
Optimization to PageFinder that makes has_parent finds perform much faster on Antti's site with 100k pages.