The performance surfaces of two classes of minimum effort adaptive filter are studied. Eigenvalue spreads of the cost functions of minimum weight vector norm and minimum output variance algorithms are examined for both estimation and feedforward control applications. Results support the widespread practical use of the "leaky LMS" algorithm.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>