The preprocessor is a function in the [Control Software] that looks through a [g-code] toolpath, and plans the router motion. G-code specifies the path the router bit should take when cutting through material, and the preprocessor ensures that the motion is smooth and fast.
Settings
There are several parameters you can tweak to customize the motion. These can be found under Setup > Advanced > PreProcessor.
Corner Velocity Control
The Speed setting allows you to control how fast you move around corners. Simply drag the slider to the left to move slower, and to the right to move faster.
For large corners, you want to slow down completely before you start moving in the other direction; but for small angles, you generally don't want to make a full stop. Set the Full Stop Angle to force the tool to come to a complete stop at angles between 180 and your setting. The default setting uses 90 degrees, which means all angles between 180 and 90 degrees force the machine to a full stop.
Curvature Speed
