As of 2015, the fastest processor in the world is the Bulldog by Advanced Micro Devices; other fast processors include the Core processors by Intel. AMD's Bulldog has a top speed of 8.429 gigahertz.
A central processing unit, or computer processor, is the hardware which carries instructions throughout a computer. The speed of a processor is measured in gigahertz, or the number of instructions it can carry each second. The number of cores also determines the speed of a processor. Multi-core processors essentially have multiple CPUs (or cores) on each chip. Most modern CPUs have at least dual cores and operate at a minimum of 2.5GHz.