Java-Web Computing paradigm changed Internet into computing environment. For Java-Web Computing and many Java applications, a new Java processor, called simultaneous multithreaded (SMT) JavaChip, is proposed to enhance the performance of previous Java processor by hardware support of Java multithreading.1 SMT JavaChip is a modified architecture with the enhanced mechanism of stack cache, instruction cache, functional units, and etc. It executes dual independent threads simultaneously and enhances instruction level parallelism. The performance of SMT JavaChip is evaluated through the simulation using JavaSim, a Java processor simulator. This research is focused to enhance the performance of Java processor by considering the characteristics of Java language and computation environment. Performance results show that SMT JavaChip can provide the execution speedup of between