A method for assigning new Diameter sessions to policy and charging rules functions (PCRFs) may be performed at a Diameter routing agent including at least one processor. The method includes receiving input regarding central processing unit (CPU) and session utilization of each of a plurality of PCRFs. The method further includes receiving Diameter message traffic requiring processing by one of the PCRFs. The method further includes identifying, from the Diameter message traffic, traffic for new sessions that have not been assigned to one of the PCRFs. The method further includes assigning the new sessions to the PCRFs based on the input regarding the CPU and session utilizations of the PCRFs. The method further includes routing the received Diameter message traffic for the new sessions to the PCRFs assigned to the new sessions.