I found an interesting article dated about two years ago where it's said that Facebook is slow and unresponsive. Well, not always. The fact is that with more than one million users is not always easy to maintain good performance rates. However, Facebook sometimes is really slow. This might be due to two key aspects. First of all, database transactions, because Facebook is a really complex web application that needs a lot of work and maintenance when it comes to query a database. So here's the first problem: server-side maintenance. Second, Facebook relies mostly on JavaScript and Ajax to perform its multiple tasks (update, delete, post etc.). This means that a web client (usually a browser) has to do a lot of work to parse and cache properly all this code. Further, more work is needed to display informative messages to the user. So here's the second problem: client-side implementation. Honestly, I don't think that Ajax and JavaScript are the only feasible alternative to ease the application's load. I think that most of the work should be tweaked up on the server-side, while using JavaScript and Ajax only in a supportive way. These are, in my opinion, the two key aspects that still need a lot of work on Facebook.