1. A method of optimizing a Business Process Management (BPM) model, said model being associated with a plurality of key performance indicators (KPI) depending on a control parameter vector comprising a plurality of control parameters, the method comprising: separating, by a processor, said control parameters into a linear control parameter vector (X) and a non-linear control parameter vector (X′), iteratively calculating, by the processor, a set of candidate values for said control parameter vector, each candidate value being determined for a preselected value of a non-linear control parameter belonging to said non-linear control parameter vector (X′) from execution of a mixed integer program (MIP) model associated with said BPM model, said plurality of key performance indicators (KPI) and said preselected value of the non-linear control parameter vector (X′), wherein calculating the set of candidate values for said control parameter vector comprises: (i) running said MIP model, which provides an approximation (X*) of an optimal value for said control parameter vector, an approximation for the Key performance indicators (c*), and an approximation (Y*) of a BPM outputs vector related to execution of the BPM model, (ii) running a simulation using the approximation (X*) of the optimal value for said control parameter vector which provides target values for the key performance indicators (c#) and target values for the BPM outputs vector (Y#), (iii) comparing the target values for the key performance indicators (c#) to the approximation for the key performance indicators (c*) and the target values for the BPM outputs vector (Y#) to the approximation (Y*) of the BPM outputs vector, and (iv) selecting said approximation (X*) of the optimal value for said control parameter vector as a candidate value for said control parameter vector in response to a precision of the approximation for the Key performance indicators (c*) and the approximation (Y*) of the BPM outputs vector with respect to the target values for the Key performance indicators (c#) and the target value for the BPM outputs vector (Y#) each satisfying a respective predefined criterion, and adjusting, by the processor, said BPM model based on at least one of said candidate values for said control parameter vector.