English: Autoptimize's cache size is getting big, consider purging the cache. Have a look at https://wordpress.org/plugins/autoptimize/faq/ to see how you can keep the cache size under control.
Dutch: De cache van Autoptimize wordt erg groot, overweeg de cache te wissen. Bekijk https://wordpress.org/plugins/autoptimize/faq/ om te zien hoe je de cachegrootte onder controle kan houden.