A bug has been perceived by many users with a functional one Android 5.0.1 Lollipop, as this causes a lot of memory consumption.
This has some unpleasant results as it closes the open applications and does continuous reloads of the home screen.
To Android Issue Tracker of Google, it seems that several devices Nexus have been affected by the above bug, such as Nexus 7 (2013), Nexus 4 and Nexus 5.
While it is normal for the device to consume about 500MB, in some cases the bug has consumed up to 1,2GB RAM!
Perhaps this is one of the reasons that Google is going to upgrade to Android 5.0.2 which has already been released for Nexus 7 (WiFi version) and is soon expected for other devices Nexus.