The CPU speed indicates how many processing cycles per second can be executed by a CPU, considering all of its cores (processing units). It is calculated by adding the clock rates of each core or, in the case of multi-core processors employing different microarchitectures, of each group of cores.
More threads result in faster performance and better multitasking.
Using big.LITTLE technology, a chip can switch between two sets of processor cores to maximize performance and battery life. For example, when playing a game the more powerful cores will be used to increase performance, whereas checking email will use the less powerful cores to maximize battery life.
Heterogeneous Multi-Processing (HMP) is a more advanced version of big.LITTLE technology. In this setup, a processor can utilize all cores at the same time, or just a single core for low-intensity tasks. This can provide powerful performance or increased battery life respectively.
When the CPU is running below its limitations, it can boost to a higher clock speed in order to give increased performance.
A larger L2 cache results in faster CPU and system-wide performance.