# Speeding up Simulations

Simulation speed is dependent on several factors in your models. If you choose a long simulation time or a small value for DT the number of calculations the software has to do increases. Also, as your model increases in complexity, as measured in number of Stocks, Flows, and Converters use in the model, the software will have more calculations per time step. Here are some things you can do to increase simulation speed in your models:

- Close all graphs and tables while the simulation is running. Then open them up after the simulation is complete to review the results. This removes the need for the software to redraw the changing graphs and tables during the run.

- Make sure Animation is turned off (click on each of the Stock, Flow, and Converter icons, in the Model Prefs under the Model Menu, to remove the box around the icon). This will remove the need to redraw the changes to the diagram during the run.

- Limit the use of numeric displays. The software will need to update each numeric display at each time step and this can slow down the operation.

- Visit the Run Specs dialog and ensure that the Sim Speed box is set to 0. Values larger than 0 will cause the simulation to slow down.

- If you observe that your computer has to use Virtual Memory to increase RAM for running the simulation, buying more RAM will speed things up. Generally you can hear the hard drive in use during the run and this would be the signal that Virtual Memory is required to run the model.