When using the PostProcessing functionality, the module process each site’s CSS and JavaScript assets. This can take additional time, depending on the site type and its dependencies.

To reduce the processing time on a new page load, the core is saving each chunk of data locally, within the data collection.

The default location for the files is /cache/wph/ This is customisable through the constant WPH_CACHE_FOLDER within the wp-config.php:

define('WPH_CACHE_FOLDER', 'cache/data');

Once the change is saved, a site cache clear is required to ensure the new location is taking effect.