A system to load test a computer system is provided. The system comprises a test script to generate transactions including a basis transaction, the basis transaction operable to initiate a conversation with a stateful enterprise java bean, and a non-basis transaction. The system also comprises a forecast and a transaction iteration calculator, the transaction iteration calculator operable to determine how often the non-basis transaction executes relative to the basis transaction. For a non-basis transaction having a forecast less than the forecast of the basis-transaction, the non-basis transaction executes once if the number given by a randomly selected number between zero and the basis transaction forecast is less than the forecast of the non-basis transaction forecast and zero times otherwise. For a non-basis transaction having a forecast more than the forecast of the basis-transaction, the non-basis transaction may execute according to another calculation. A script controller is also provided.