Comparisons of different versions of an application may be compared using a behavior model of the application. A behavior model may be derived from n-gram analysis of observations of the application in production. The behavior model may include sequences of inputs received by the application or functions performed by the application, where each sequence is an n-gram observed in tracer data. Each n-gram may be coupled with a resource consumption to give a behavior model with performance data. A regression analysis may apply a behavior model derived from a first version of an application to the performance observations of a new version to create an expected performance metric for the new version. A similarly calculated metric from a previous version may be compared to the metric from a new version to determine an improvement or degradation of performance.