Best-case performance

The term best-case performance is used in computer science to describe the way an algorithm behaves under optimal conditions. For example, a simple linear search on an array has a worst case performance O(n) (for the case where the desired element is the last, so the algorithm has to check every element; see Big O notation), and average running time is O(n/2) (the average position of an element is the middle of the array), but in the best case the desired element is the first element in the array and the run time is O(1).

Development and choice of algorithms is rarely based on best-case performance: most academic and commercial enterprises are more interested in improving average performance and worst-case performance.