This paper introduces TUTW - Temporal Uncertainty Time Warp - a control engine designed for an exploitation of temporal uncertainty (TU) in general optimistic simulations, and concentrates on an agent-based implementation of TUTW which enables distributed simulations over the Internet. A novel concept in TUTW is an event model where time intervals are attached to events instead of classical punctual or "precise" timestamps. All of this reflects typical system specifications where the occurrence time of events cannot be known with complete certainty. TUTW takes advantage of TU by resolving events so that the number of rollbacks is reduced. The simulator performance can thus be improved without necessarily compromising the accuracy of the results. The current agent-based implementation is based on Java and the ActorFoundry middleware. The implementation is totally portable and makes it possible to configure a distributed simulation virtual machine which includes heterogeneous computing platforms. The paper includes an example to illustrate the application of TUTW.