The standard OPcache extension is strongly recommended; since Moodle 2.6, it is the only solution officially supported by PHP developers. The benefits are increased performance and significantly lower memory usage.
The OPcache extension is distributed as part of PHP 5.5.0 and later. It is available also for older stable PHP releases from PECL under the original name ZendOPcache.
[opcache] opcache.enable = 1 opcache.memory_consumption = 128 opcache.max_accelerated_files = 4000 opcache.revalidate_freq = 60 ; Required for Moodle opcache.use_cwd = 1 opcache.validate_timestamps = 1 opcache.save_comments = 1 opcache.enable_file_override = 0 ; If something does not work in Moodle ;opcache.revalidate_path = 1 ; May fix problems with include paths ; Experimental for Moodle 2.6 and later ;opcache.fast_shutdown = 1 ;opcache.enable_cli = 1 ; Speeds up CLI cron ;opcache.load_comments = 0 ; May lower memory use, might not be compatible with add-ons and other apps.
When using IIS you will need PHP 5.5 and you will need to add the extension for opcache under the ExtensionList section of the php.ini file.
[ExtensionList] ... zend_extension=php_opcache.dll