Portable mobile code is often executed by a host virtual machine using just-in-time compilation. In this context, the compilation time in the host virtual machine is critical. This compilation time can be reduced if optimizations are performed ahead-of-time before distribution of the mobile code. Unfortunately, the portable nature of mobile code limits ahead-of-time optimizations to those that are machine-independent. This work examines the effect of machine-independent optimizations on the performance of mobile code applications. All experiments use the SafeTSA Format, a mobile code format that is based on Static Single Assignment Form (SSA Form). The experiments, which are performed on both the PowerPC and IA32 architectures, indicate that the effects of performing classical machine-independent optimizations are—in fact—quite machine-dependent. Nevertheless, the results demonstrate that applying such optimizations in a mobile code system can be beneficial. Copyright © 2009 John Wiley & Sons, Ltd.