Practical Clojure

Chapter 14. Performance

In principle, Clojure can be just as fast as Java: both are compiled to Java bytecode instructions, which are executed by a Java Virtual Machine. Clojure's design is careful to avoid features—such as continuations or a Common Lisp-like condition system—that would severely compromise performance on the JVM. But Clojure is still a young language, and has not had the benefit of hundreds of thousands of programmer-hours spent optimizing the compiler. As a result, Clojure code will generally run slower than equivalent Java code. However, with some minor adjustments, Clojure performance can usually be brought near Java performance. Don't forget that Java is always available as a fallback for performance-critical sections of code. ...