All arithmetical and logical procedures inside a computer/server configuration are addressed by its Central Processing Unit, or CPU. This hardware element is typically called the "brains" of the PC as well. The pace at which the CPU executes system instructions is usually referred to as its speed and it's measured in Hertz. The faster the processing unit is, the speedier scripts and web apps shall be executed, although the overall performance of the latter is determined by other things as well - the read/write speed of the hard disk, the amount of physical memory, the network connection, and many others. All new CPUs have multiple cores, which work together. For that reason, the efficiency and the workload that a CPU can take care of increase, because every single core can process a number of tasks individually and several cores can handle 1 task that cannot be processed by 1 core.