Every new installation of Android firmware results in some battery drain for some users.
This is almost always because the update was applied over the top of existing firmware rather than installed 'clean'.
It seems that we can't have an Android update without something going wrong with either Wi-Fi, Bluetooth or both.
Try the usual range of solutions: toggle airplane mode on and off, forget and reconnect to the network, reboot your phone, restart your router or switch between the Wi-Fi frequency bands.
But some users have encountered a range of issues, including freezes, crashes, stutter and lag. Installing updates on top of updates on top of updates can eventually cause problems, so a factory reset might be on the cards, but first look at your apps to check they’ve been updated to Lollipop.
As with any performance issues, try switching off anything you don’t need to see if you can identify a specific cause.
You can do this via the Nexus 7 (2013) owners have reported some bugs with video playback following the update to Lollipop.
If this fails, you may have to wait for a patch from Google for the permanent solution.Assuming you haven’t left your device in direct sunlight or near a wicked child with a magnifying glass, overheating is often a side-effect of really hammering the phone with apps such as 3D games.