Instructions per second (IPS) is a measure of a computer's processor speed. Many reported IPS values have represented "peak" execution rates on artificial instruction sequences with few branches, whereas realistic workloads typically lead to significantly lower IPS values. The performance of the memory hierarchy also greatly affects processor performance, an issue barely considered in MIPS calculations. Because of these problems, synthetic benchmarks such as SPECint or Dhrystone are now generally used to estimate computer performance in commonly used applications, and raw IPS has fallen into disuse.