This paper presents an automatic variable speed processor (VSP) with the ability to change its clock rate on a cycle by cycle basis, according to program instructions being in the pipeline. To demonstrate the concept, we are using an Altera Nios processor coupled to a variable period clock synthesizer (VPCS) that is used as our variable speed clock generator. The clock period variations give a speedup, with little impact on energy consumption, and that speedup can be traded for energy reduction using voltage scaling. Our proposals are supported with a prototype implemented on the Altera embedded system development board that embeds a Strafix FPGA.