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HAVE computers stopped getting faster? If you looked only at the clock speeds of microprocessor chips, you might well think so. A modern PC typically has a processor running at 3.0GHz (3 billion clock ticks per second), little changed from a PC made three or four years ago. Clock speeds, which used to double every couple of years, have stopped increasing because as chips are clocked at higher speeds they become difficult to cool and much less energy-efficient. Instead, extra oomph has been added in recent years by packaging multiple processing engines, or “cores”, inside a single chip. Modern PCs and laptops typically have dual-core processors (such as the Intel Core i3) and some have quad-core or even six-core chips.