Each time eZ Publish is called to load a page, run a cronjob etc, the code checks whether modules folder exists or not in extension.

This is done in lib/ezutils/classes/ezmodule.php in eZModule::activeModuleRepositories(). Module's views don't change every day. This is why we can create a cache file which will remove a great number of call to file_exists.

The attached file creates a cache file in eZSys::cacheDirectory() which will reload itself every 6 hours.

It would be interesting to add to setup/cache view in the admin siteaccess the possibility to flush this cache file.