The Java programming language and the underlying virtual machine model have introduced new complexities for compilation. Various approaches ranging from just in time (JIT) compilation to ahead of time (AOT) compilation are being explored with the aim of improving the performance of Java programs. The hurdles facing the achievement of high performance in Java and the strengths and weaknesses of different approaches to Java compilation are addressed in this paper, specifically within the context of SGI’s effort to provide a high-performance Java execution environment for its computing platforms. The SGI JIT compiler and prototype AOT compiler are described, and performance results are presented and discussed.