1. A method for controlling spark timing in an internal combustion engine, such method comprising: determining background borderline spark timing at a background computational rate, such borderline spark timing being a function of determined air charge and engine speed; and, determining foreground borderline spark timing at a foreground computational rate, such foreground computational rate being higher than such background computational rate, the foreground borderline spark timing being a function of air charge determined at the foreground computational rate and engine speed measured at the background computational rate.