1. A process controller for use in controlling a set of process equipment performing a process, comprising: a set point input that receives a set point for a controlled process variable within the process; a process variable input that receives measured values of the controlled process variable; a process model that produces one or more predicted values of the controlled process variable during each of a number of execution cycles; a control signal generator coupled to the process model and to the set point input that operates during each of the number of execution cycles to use the set point and the one or more predicted values of the controlled process variable produced by the process model during the execution cycle to produce a control signal for controlling the process equipment to thereby drive the controlled process variable towards the set point; and a model bias correction unit coupled to the process variable input and to the process model, wherein the model bias correction unit determines a model correction to be applied by the process model to produce the predicted values of the controlled process variable; wherein the control signal generator and the process model operate successive execution cycles at an execution rate; wherein the process variable input receives measured values of the controlled process variable at a rate less than the execution rate of the control signal generator and the process model; wherein the model bias correction unit produces a new model correction based on a previously predicted value of the controlled process variable for a particular time and a newly received measured value of the controlled process variable for the particular time during an execution cycle associated with the receipt of a new measured value of the controlled process variable at the process variable input; and wherein the process model offsets one or more calculated predicted controlled process variable values with the new model correction to produce the one or more predicted values of the controlled process variable only during the execution cycle associated with the receipt of the new measured value of the controlled process variable at the process variable input.