More useful info, thanks for taking the trouble :) I guess the final ratio figure - 3.82 sounds at fist a little disappointing, until you realise that is from the POV of the fastest machine. If the ratio were taken from the POV of a medium machine the result might be a little more balanced. Of course, the ideal test would be made using an array of identical machines, but obviously that can't be done here, which is why I would suggest the ratio be measured from a medium machine.