Google has started seeding out the Android 5.1 Lollipop update to but many are still concerned with the reported memory leak issue that hasn't been fixed with it.
The good news is Android SDK manager pushes the new Android 5.1.1 Lollipop update as part of the SDK package. For now it nests under the development platform and also ensures a quick release to the devices running Android 5.1 for now.
Enthusiasts should be banking on this version to get the memory leak issue that drains battery and deteriorates performance fixed.