as everyone may have noticed the update that Sony provided us for android 5.1.1 is much more fluid and fast
Verifying the new firmware came across Zram enabled by default, which does not we obtained in previous firmwares
So Sony is adding many other features to optimize our dispoositivos, that's pretty technical but were not mentioned in its changelog of the new firmware
I have updated my SDK version using the update to version 21. This new release is coming with a new appcompat the is not allowing previous features from the ActionBar like the icon in the top, requiring to introduce the new concept of toolbar.
So, I prefer the previous implemented behaviour, and changing my app to adapt to this new concept requires some time.