Default Advice ftf back to 4.2

Hello community, congratulations for your work, I'm Italian and I read quite a while, I had a question, I upgraded to 4.4 but I am disappointed 10.5.A.0.230 the lag and battery, I would like to go back to 4.2 and was very good for me , but I remember that there was a bug on the battery percentage, I know indicate that the firmware ftf not experience this problem with the battery, can not remember which update it was!
Thanks a greeting.