Performance Difference Between ipp Versions

Hi all,

i use two algoritms (Foreground/Background Segmentation Using Histogram Model and Mixture of Gaussians) to obtain foreground and i use 3 different ipp versions:First one is ipp 6.0.0.062,second one is ipp 7.1.1.119 and last one is ipp 8.0.0.083.I expected more performance  with increased versions but i saw that ipp 6 is best,then ipp 8 and last one is ipp 7.What is the reason of this situations????