1. A method for image reconstruction, comprising: receiving measured data from an imaging system; determining a preliminary image update in a particular iteration of a plurality of iterations based on one or more current image variables computed using one or more subsets of the measured data in the particular iteration; determining at least one momentum term using the one or more current image variables computed in the particular iteration, one or more further image variables computed in one or more iterations preceding the particular iteration, or a combination thereof, based on a convergence rate, wherein the convergence rate is O(I/(mk)^2), and wherein k represents a number of the plurality of iterations and m represents a number of the one or more subsets of the measured data; replacing a Lipschitz constant in the at least one momentum term with a suitable diagonal majorizer; determining a subsequent image update using the preliminary image update and the at least one momentum term with the suitable diagonal majorizer; and iteratively computing the preliminary image update, the subsequent image update, or a combination thereof, for the plurality of iterations until one or more termination criteria are satisfied.