Disclosed herein are systems and methods for simulating an environment over a plurality of intervals of in-simulation time by using a two-part data structure to represent agents or entities in the simulation. A system may create and store a data structure representing an agent in the simulation, wherein a first portion of the data structure represents characteristics of the agent at a present interval and a second portion of data structure represents characteristics of the agent at a future interval of the simulation. Also disclosed herein are systems and methods for executing a multi-agent simulation using multiple processing threads. A system may group a plurality of agents in the simulated environment into subsets associated respectively with nodes of the simulated environment, assign the subsets to respective separate processors of the system, and execute the simulation using separate processing threads associated respectively with the separate processors.