1. A controller for directing operation of a system performing a process, having multiple process parameters (MPPs), at least one of the MPPs being a controllable process parameter (CTPP) and one of the MPPs being a targeted process parameter (TPP), and having a defined target value (DTV) representing a limit on an actual average value (AAV) of the TPP over a defined moving time period of length TPLMV, with the AAV computed based on actual values (AVs) of the TPP over the defined period, comprising: a storage medium configured to store historical data representing the AVs of the TPP at various times over a prior time period (PTP) having a length of at least TPLMV and extending from a prior time of T -AAV1 to a current time T 0 ; and a processor configured to (a) to predict future average values (FAVs) of the TPP over a future time period (FTP) having a length of at least TPL AAV and extending from the current time T 0 to a future time T AAV1 , on or after which the TPP will move to steady state, wherein the FAVs of the TPP over the FTP are predicted based on (i) the stored historical data representing the AVs of the TPP at various times over the PTP and (ii) the current values of the MPPs, (b) determine a target set point for each CTPP based on (i) the predicted FAVs of the TPP over the FTP, (ii) the current values of the MPPs, and (iii) the DTV, and (c) direct control of each CTPP in accordance with the determined target set point for that CTPP.