Well, High Performance means better handling on a road and turns, maintaining soft ride ... some people here went from Diamaris to Vredestein's.. and they really like it... althrought Diamaris have V rating, but Vredesteins have Z rating , what means Vredesteins perform better even on a high speed. I'm personally using them on my M5, and waiting for the moment when my Diamaris will be worn out, so I can put Vredesteins on X.
I also had experience with Michelin Latitude HP- didnt like them, sold them... they are not bad in summer ( but a little bit heavier then diamaris) and on wet road, but they did not perform good even on light snow, not to mention ice.