A variety of performance control mechanisms are disclosed, allowing a user of a processor-based system to adjust performance criteria such as processing speed and fan speed. A performance control apparatus includes one or more user-accessible knobs and a display. The knob(s) enable the user to select from a variety of processor and fan speed settings. Other performance-related criteria may also be controlled using the knobs. The display communicates the effect of a change in performance criteria in a manner useful to the user. A performance control application program enables the user to independently pre-select performance criteria for each application program or group of application programs. A performance control icon provides the ability to select performance criteria from within an application program.