for now the best is the cm9 lp7 kernel.. there is another kernel called super kernel i think.. but u cant use it when ur on aosp rom such as cm9 , aokp or paranoid android rom....
if u wna save battery life..  use juice defender

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Added on July 1, 2012, 12:12 am
not from samsung tho but for sure in the xda community for sure there will be
codeworkx dev for cyanogenmod said that they're currently working on creating a rom most likely a whole new cyanogen mod mayb cm10 @.@ fr the galaxy s2... theres already jellybean for g_nexus which uses dual core tiomap chipset.. i think will be there for the i9100 and also the i9100g running the same chipset as in g_nexus