All arithmetical and logical procedures in a computer/server configuration are tackled by its Central Processing Unit, or CPU. This hardware part is sometimes called the "brains" of the computer system too. The pace at which the CPU completes system instructions is typically referred to as its speed and it's measured in Hertz. The quicker the processing unit is, the speedier scripts and web programs shall be executed, although the overall performance of the latter depends upon other things as well - the read/write speed of the hard disk, the amount of physical memory, the network connection, and so forth. All modern CPUs have a number of cores, that work together. As a result, the efficiency and the workload a CPU can take care of increase, since each core can process several tasks separately and a number of cores can handle a single task that can't be processed by one core.