Android 5.1 fixed a lot of issues, but apparently a persistent memory leak was not one of them.
A rather lengthy issue tracker on the Android Open Source Project indicates that many Nexus 5 owners are still seeing significant memory resources draining, an issue that first popped up with Android 5.0 and has persisted since.
There is some hope, as a post from someone on the Android development team says the problem has “been fixed internally,” though there isn’t a timeline for when it will be released to the public.
The problem can be diagnosed by going to Settings > Apps, then scrolling to Running. If the system memory is eating up an unsually large amount of RAM (over a gigabyte, when no apps are running), then you may be bitten by this bug also, which can slow your device to a crawl and crash apps. The best bet is to restart the device from time to time, though that’s obviously an annoying, band-aid approach.
The impact on you: This shouldn’t hold you back from jumping up to Android 5.1 if you’re on a Nexus device, as it definitely speeds up performance and fixes many performance issues, such as a rather annoying bug that kept crashing the Contacts app. This may explain why hardware partners and carriers have been slow to update to Android Lollipop.
This story, "Memory leak complaints still abound after Android 5.1 update" was originally published by Greenbot.