The earliest computing devices were built to perform automatic computations and, as computers grew in power, they became increasingly popular because of how much and how fast they could compute. Even today, this essence lives on in our anticipation that computers can execute our business calculations faster than before by means of the applications we run on them.

Compared to performance analysis and optimization at a smaller component level, as we saw in previous chapters, it takes a holistic approach to improve performance at the application level. The higher-level concerns, such as serving a certain number of users in a day, or handling an identified quantum of load through a multi-layered system, requires us to think about how the components fit together and how the load is designed to flow through it. In this chapter, we will discuss such high-level concerns. Like the previous chapter, by and large this chapter applies to applications written in any...