1. A simulated virtual computer system for testing the performance of a program, said virtual computer system executing on a real computer system, the virtual computer system comprising: a CPU emulation module; a first plurality of software modules that simulate hardware devices in the virtual computer system; a second plurality of software modules that simulate software executing in the CPU emulation module in the virtual computer system; and a system kernel module that manages the virtual computer system environment, wherein the program to be tested is executed in the virtual computer system, and wherein the system kernel logs accesses to the resources simulated by the first and second plurality of software modules.