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 that occur relatively frequently in the frequently call stacks; identifying clusters of the identified function call patterns based on an automated SVM classifier; and ranking the clusters based at least in part on the number of occurrences of function call patterns occurring within the clusters.