1. A non-transitory computer-readable medium having stored therein a performance abnormality analysis program that causes a computer to execute an operation including an analysis of the performance abnormality of a system composed of a plurality of computers, the operation comprising: a resource utilization situation acquisition step that acquires a resource utilization situation of the system; a request occurrence frequency acquisition step that acquires an occurrence frequency of a request which is transmitted to the system; a processing time acquisition step that acquires a time period required when the system processes the request transmitted to the system; a performance abnormality existence/nonexistence determination step that determines the existence/nonexistence of the performance abnormality; and a condition analysis step that analyzes a condition of a case under which the occurrence rate of the performance abnormality is high based on information related to the resource utilization situation acquired in the resource utilization situation acquisition step and the occurrence frequency of a request acquired in the request occurrence frequency acquisition step, and information related to the existence/nonexistence of the performance abnormality determined in the performance abnormality existence/nonexistence determination step, the condition analysis step generating, when branching a parent node that represents a situation of a decision tree to two child nodes using the method of decision tree, the decision tree using an evaluation function which performs branching such that most of normal samples which belong to the parent node are contained in the one child node, and most of abnormal values which belong to the parent node are contained in the other child node, determining a condition of a case under which the rate of the performance abnormality is high.