Android 5.1.1 is expected to fix a memory leak affecting the OS for quite a long time.
android-5.1.1-sdk
Android 5.0 has been pretty stable for an update that brings major changes to an operating system, but Android 5.0.1 introduced a pretty major issue in the form of a memory leak that has been causing performance issues for many users. Android 5.1 fixed this memory leak, only to introduce a new memory leak problem. According to Google, this new leak was already fixed soon after being discovered, but the internet giant gave no details about when the fix would be coming to end-users.
However, it looks like the wait might not be too long this time around, and the fix could arrive as part of Android 5.1.1. Google is yet to officially announce the new version of the OS, but Android 5.1.1 is now the default version for developers using the Android SDK Manager, suggesting the OTA update could start rolling out in the very near future. Android 5.1.1 is also expected to introduce a built-in VPN service, and will no doubt bring along more optimization to what is the most beautiful and consistent version of Android yet.