These instructions are from my post a while ago:

Slowing your heli down
Method 1:
Adjust the Sim Rate Multiplier. Open the program, click on the options button, click on the physics button and click on the field that is indicated by the Sim Rate Multiplier and change this to anything less than 1.00. Now on my computer this field doesn't work exactly as it should, but you'll likely get one of these settings, so try it