1. A method of identifying issues related to slow performance in computer programs, comprising: collecting execution traces from multiple computers, the execution traces corresponding to multiple execution instances that have exhibited slow performance; processing the execution traces to identify function call stacks; mining the function call stacks to identify function call patterns having a number of occurrences in the function call stacks above a specified threshold identifying clusters of the identified function call patterns based on an automated support vector machine (SVM) classifier; and ranking each respective cluster of the clusters based at least in part on a number of occurrences of the identified function call patterns occurring within the respective cluster.