Java Platform Performance is completely devoted to this matter. Because it is published in Addison-Wesley's Sun Java series, it is also in some ways Sun's semi-official statement related to this critical issue. 

Any book that deals with performance and Java has to narrow its focus in certain respects; the whole issue of Java performance is too much for a single book. For example, think of general language and environment-independent performance techniques (such as the use of buffering instead of single element processing). Also consider the huge field of Java programming: GUI programming, multithread programming, and distribution with different programming models. Think of the different Java technologies like Jini and EJB. While all of this is "Java," each of these areas has its own specific performance issues and tricks. 

Because Java Platform Performance contains only 230 pages, it must be very focused; let's see on what. 

The first part of the book is called "Strategies." These three chapters (amounting to fewer than 40 pages) each deal with one of the following issues: 

• What performance is (runtime performance, RAM footprint, etc.)
• How achieving good performance is linked to the complete software development process
• How to benchmark and profile a software system

• I/O performance. Mostly discusses buffering and the tricky business of object serialization.
• RAM footprint. Discusses how to measure and optimize object size.
• Class loading. Discusses when classes are really loaded and encourages programmers to run multiple threads in one VM instead of multiple VMs.
• Object mutability. Discusses different aspects related to this issue: e.g., String versus StringBuffer performance, how immutable objects or immutable interfaces to mutable objects can prevent the expensive invocation of clone() , etc.
• Algorithms and data structures. Discusses choosing the right algorithms (iteration, recursion) with the help of benchmarking, and selecting the appropriate data structure type from the JDK 1.2 collection framework.
• Using native code. Discusses performance advantages (and disadvantages) using JNI.
• Swing programming (two chapters on this). One chapter discusses renderers and the Swing model; the other deals with more general Swing design and implementation techniques to achieve a responsive user interface.
• Deployment. Discusses how JAR files can help you save download time.

The discussion of garbage collection, in contrast, does not go into the direction of how garbage collection is implemented in Java. Instead, the authors discuss how references are logically maintained in Java: How does an object become unreachable? What is the process of garbage collection (finalization, freeing of memory, etc.)? What is the idea behind the reference abstractions introduced with the Java 2 platform? 

As you can see, Java Platform Performance focuses on those Java performance issues that are relevant to all Java programmers. The only exception are the two chapters about Swing programming, which might be not so interesting for Java server-side programmers. 

There is one issue that should have been covered: how well Java performs when it is compiled to machine code. Perhaps this is not included because compiled Java is at odds with Sun's official policy of "compile once, run everywhere." Perhaps you shouldn't expect this issue to be raised in a book published in the Sun Java series. 

Java Platform Performance is a good book that addresses all relevant issues in a way that is easy to follow for someone new to Java performance. An advanced Java programmer might find it a little disappointing, however, because he or she might have already heard most of the issues. There are no radically new ideas in this book. But then, new ideas regarding Java performance improvements might not even exist. 

Angelika Langer develops and teaches classes on Java, C++, multithreading, and internationalization. She is an internationally recognized speaker and served on the ANSI/ISO C++ Committee from 1993 to 1998. Klaus Kreft is a software architect and senior consultant with 15+ years of experience in industrial software development. He currently works for Siemens Business Services in Germany. Langer and Kreft are authors of "Standard C++ IOStreams and Locales" (Addison-Wesley, 2000) and are columnists for the C/C++ Users Journal.