This is the company that bragged about having 18,000 classes for their iOS app [1] and having to patch the Dalvik Virtual Machine to support new features in their Android app [2]; they are not infallible.
IiRC they aso exploited an Android bug to give themselves more memory. Facebook is woefully buggy and slow that many people are now either using the website or alternative wrapper apps that don't drain their battery immensely.