I have a really old Nexus 7 (https://en.wikipedia.org/wiki/Nexus_7_%282012_version%29) and upgrading that to Lollipop basically made it unusable. It was terribly slow.
I unlocked the bootloader and reflashed with 4.4.4 (https://dl.google.com/dl/android/aosp/nakasi-ktu84p-factory-2c6e4d6f.tgz) and that was much better.
But that’s really no fun so I decided to give CyanogenMode a shot (http://download.cyanogenmod.org/?device=grouper&type=). It was a bit overwhelming at first to work out that:
- nakasi is the codename for that tablet at Google while grouper is the codename for the CM team
- CM 11.0 is based on Android 4.4.4
- M vs N vs stable vs snapshot … (http://wiki.cyanogenmod.org/w/Release_Versioning)
I finally settled on this http://download.cyanogenmod.org/get/jenkins/90453/cm-11-20141112-SNAPSHOT-M12-grouper.zip but that’s no fun either so I built it from scratch. https://wiki.cyanogenmod.org/w/Build_for_grouper
Everything is all documented and there are even steps to make sure the GMS apps are installed so the resultant build is very much usable.
That was fun.