Acceleration factor for SQS and Nes relative to SQS-1 (note the different y-axis scaling). (a) SQS-66 reaches a suboptimal limit cycle and cannot further improve the objective, while SQS-{33, 22, 11} achieve the same objective as 104 iterations of SQS-1 in {321, 469, 922} iterations, respectively, and provide AF approximately equal to M. (b) On the other hand, Nes-18 (and greater M) exhibits unstable, nonmonotonic acceleration, while Nes-{11, 9, 6} achieve the same objective as 104 iterations of SQS-1 in only {28, 34, 50} iterations, giving AF of {357, 294, 200}, respectively.