LazyMouse

From ZBrush Info

The Lazy Mouse gives the artist more control over their brush stroke. It allows the artist to work with a greater degree of refinement than by hand alone. Using the Lazy Mouse artists can create very precise and controlled brush strokes with ease!

When using lazy mouse, you are effectively dragging the paint cursor behind the mouse cursor, with a piece of digital string (shown in red) connecting the two. Jitter in the mouse cursor will be greatly reduced at the other end of the string, and the line of the string indicates exactly the direction the paint cursor will travel in.

Small wobbles in your drag will become so small in the stroke that they will be unnoticeable. The 'digital string' really is like string. If you double back on your path and get close to the current stroke position, your string will get 'slack', and won't cause the stroke cursor to move. This is how you get sharper corners. My hand wasn't really as steady as the arrow implies :-).