By increasing the speed of each simulation, you can increase the number of simulations that OptQuest runs in a given time period. Some suggestions to increase speed are:
Use Extreme Speed when practical.
Use precision control in Crystal Ball to stop simulations as soon as they reach a satisfactory accuracy
Reduce the size of your model
Increase your system's RAM
Reduce the number of assumptions and forecasts
Quit other applications
The Oracle Crystal Ball User's Guide discusses these suggestions in more detail.