Clojure is a safe, functional programming language that brings great power and simplicity to the user. Clojure is also dynamically and strongly typed, and has very good performance characteristics. Naturally, every activity performed on a computer has an associated cost. What constitutes acceptable performance varies from one use-case and workload to another. In today's world, performance is even the determining factor for several kinds of applications. We will discuss Clojure (which runs on the JVM (Java Virtual Machine)), and its runtime environment in the light of performance, which is the goal of this book.

The performance of Clojure applications depend on various factors. For a given application, understanding its use cases, design and implementation, algorithms, resource requirements and alignment with the hardware, and the underlying software capabilities is essential. In this chapter, we will study the basics of performance analysis, including the following: