With criticisms like that, I think your expectations are unrealistic. Considering the size of their userbase, their chat server is quite an accomplishment. And minor replication artefacts are hardly a big issue.<p>In short, if FB had incompetent or even "just" competent engineering, they would not have close to 400 million users. And yet they do, and I have never noticed the site performing slowly. They're not Google, fine, but they have an excellent team and if you're not impressed by their performance I wonder what you would be impressed by.