The disclosure describes various aspects of quantum computer simulators. In an aspect, a method for characterizing a quantum computer simulator includes identifying simulator processes supported by the quantum computer simulator, generating, for each simulator process, characteristic curves for different gates or quantum operations, the characteristic curves including information for predicting the time it takes to simulate each of the gates or quantum operations in a respective simulator process, and providing the characteristic curves to select one of the simulator processes to simulate a circuit, quantum program, or quantum algorithm that uses at least some of the gates or quantum operations. In another aspect, a method for optimizing simulations in a quantum computer simulator is described where a simulator process is selected for simulation of a circuit, quantum program, or quantum algorithm based on characteristic curves that predict a time it takes for the simulation to be carried out.