a) Parallelization problem
Symptoms: One core is loaded during simulation (Task Manger -> “Perfomance” tab -> Open Resource Monitor).
Solution: Check that parallelization optimization is enabled in ModelRisk settings. To do this: in the lower right corner of the desktop, call the context menu on the ModelRisk icon (see the image below) and select “Advanced Settings”:
In the window that appears, use the “Optimization options” button to call the optimization window and make sure that the “Disable distribution optimization” switch is in the “Off” position (image below):
You should also check Excel's parallelization settings:
b) Slow start of the simulation
Symptoms: A lot of time is spent on the preparation steps of the simulation
Solution: In some models, using the "Model Analysis Acceleration" option may not be justified due to the structure and formulas used. Try to switch the "Disable Model Analysis Acceleration" option to the “On” position (image below):