Methods and systems consistent with the present invention provide a statistical profile of execution characteristics of a program, then use that statistical profile to regenerate code at run-time. When the information in the statistical profile is insufficient to make an optimization decision, methods and systems in accordance with the present invention may use the statistical profile plus additional information described below to determine a minimal level of instrumentation required to answer a particular optimization question. They then add at run-time the minimal instrumentation required to decide an optimization question, continue running the program for a period of time, and then analyze the resulting instrumentation data. These systems may either iterate the process to get more data or use the available data to compile a more highly optimized program.