Fastmouse is a cursor accelerator for those who like to minimize arm motion. It is particularly handy for those optical mice which require large gestures to move the cursor any distance. If the change between mouse positions exceeds a given threshold between samplings, that change is amplified. Two methods are available for amplification: (1) linear acceleration (scaling by a constant), (2) quadratic acceleration (the change is multiplied by itself, then scaled). Threshold and acceleration methods are specified by user profile options.

FastMouse can be turned on or off from either a command-tool or your user profile (the most recently processed one prevails). The UserProfile option FastMouse.Enabled is a Boolean+ that defaults to UNSPECIFIED (means keep on doing whatever it was doing). The command-tool command "FastMouse" takes one argument, which should be either "on" or "off" (e.g., "FastMouse on" or "FastMouse off").