Gravatar Cache: Enable caching for Gravatar. What is Gravatar?
Gravatar Cache Cron: Enable automatic caching of Gravatar instead of caching on the first visit.
Gravatar Cache TTL: Cache duration time.
Localize Resources: This is a very useful option if the optimization result requires creating resources like Facebook or Google locally. This enables you to shorten the site loading time and waiting.
Localization Domains: As you can see in the list of all the files being localized, if there is another file you are pulling from an external source, you can enter the complete URL here, as you can see in the example of the existing ones.