thanks for the tip from someone here. finally tried and tested Abyss kernel. I think it's the best available so far.

previously tried perseus - lots of features, and the developer is top notch but somehow don't feel very smooth at all. in theory this should be the best one, but somehow feel laggier than stock.

tried redpill also, no problems at all. quite good in fact but imo bested by abyss.

haven't tried neak or neocore because they don't support exfat yet. probably wont try neak, didnt have good feel during the s2 days. also dont like kernels that come with their own tweaking app. prefer kernels that support the general ones like Android tuner, i mean why reinvent the wheel?

abyss so far fits me fine. i underclock it quite a bit (i know what ppl say about UC having minimal effect on battery life, maybe so, but the phone definitely runs cooler) pity it gets little exposure because it's hosted in an italian forum and not on xda.