Gravatar Cache: You enable caching for gravatar.
Gravatar Cache Cron: You enable automatic caching of the gravatar and not on the first visit.
Gravatar Cache TTL: cache lifetime.
Localize Resources: This is a very useful option if the optimization result requires the creation of resources for example Facebook or Google locally. This allows you to shorten site loading and waiting times.
Localization Domains: as you can see in the list that all files are localized, if there is another file that you drag from outside you can enter the complete url here as you have an example to see which ones already exist.
