Our "no-internet" wiki takes a long time to load

Hello XWikiers,
Users on non-internet network: We have a youtube video, and a custom font that is timing out on the front page. (Good, its supposed to be secure area)

Does XWiki load embedded videos etc async or synchronously?

If its loading them non-async, then that tells us right away why the wiki is so slow (ONLY USERS ON NON-INTERNET network since theyre trying to load a page that… cant get all of its files).

We want users on internet network and non-internet network to have roughly the same loading time. (as best possible)