An example system for a performance gains predictor includes a counter engine to determine a number of events during an application session of a computing system utilizing a first processor, a metrics engine to calculate a number of metrics for the first processor based on the number of events, a factor engine to determine a number of factors of the first processor that can affect the number of metrics based on an evaluation of the computing system, and a performance engine to predict a performance change of the computing system utilizing a second processor based on the number of factors.