ABOUT FACEBOOK
Facebook is a social media and technology company.
ISSUES WITH FACEBOOK IN CHINA
Facebook is blocked in China. This means that resources loaded from Facebook-associated domains - including widgets, trackers, messenger, and more - are also blocked and therefore fail to deliver properly to visitors in China.
These blocked resources negatively affect how well, and fast, the rest of the page renders. Because the browsers in China will continue trying to access these files even though they are blocked, other resources (that may not be blocked) will be affected in their ability to load sequentially thereafter.