Control circuitry controls the operations of a central processing unit, CPU, which is associated with a nominal clock frequency. The CPU is further coupled to an I/O range and configured to deliver input to an application. The control circuitry controls the CPU to poll the I/O range for input to the application. The control circuitry also monitors whether or not each poll results in input to the application and adjusts a clock frequency at which the CPU operates to a clock frequency lower than the nominal clock frequency if a pre-defined number of polls resulting in no input is detected.