Well i was searching for this Forum from the time i updated ma phone to JB.
To start with all that was supposed to be overcome(butter effect, smooth scrolling, super fast navigation etc...) has increased.
I have seen ma phone drastically slowdown and it takes approx 4 seconds to open up call logs or message logs.
I did a factory restet too. It resolved the issue for about 20 mins. Later same pain.
I thought there was some problem with ma phone but friend of mine who had S3 too updated it same day and guess what, he calls me and logs the same issue.
processor consumption is bad. it is always 700mb or more consumption. I have the basic apps and nothing additional in my phone, still it is slower than basic android phones.
I liked ICS better and faster. God some one please help us.