Not only has Facebook always run their business in a vastly superior way in terms of cost in the system, they never went through something equivalent to the fail whale mess that plagued Twitter. Facebook's performance problems have been minor compared to what Twitter has gone through.
As a business, Twitter should be far more profitable than they are, their profit margin is 1/3 that of Facebook at the same level of sales (2011 for Facebook), despite having 1/2 the number of users that Facebook had at that point time.