Very few sites face the technical challenges that Facebook does. Recent data shows that it has replaced Yahoo as the #2 most visited site on the web.

Obviously, this poses some very unique and serious technical challenges. Recently, Jason Sobel wrote a great blog post titled “Making Facebook 2x Faster” about how they broke the challenges down into 3 parts—network time, generation time, and render time—and tackled each problem separately. The combination of these three metrics, which, honestly, is the one metric every busy site owner should be monitoring, is what they call “Time-to-Interact” —that is, the time that a user has to wait for something to happen.

The interesting thing is that Facebook is obviously at the physical limits of all the current techniques and technologies of building highly scalable web applications. This means that, instead of being able to follow others, they are having to blaze the trail themselves.

The blog post is lengthy but high level; while there is no discussion of the exact techniques or technologies they deployed, it is well worth the read. The techniques they used might not apply to many sites, but every web architect needs to see the problems they face and understand why they are important.