few things that will help you get the best experience possible. Not all phones are created equal tho.
Disable Nuplayer
Will help Facebook Messenger etc to run better on a Lollipop phone.
Go to under Settings > Developer options. where you find Use Nuplayer (experimental) and disable that (untick). And restart phone after.
You have no Developer options under Settings? Follow THIS
Wipe Cache Partition
Simply follow the instructions HERE. This step will not remove any personal content on your phone, it will merely make sure that the environment on your phone is as nice and clean as possible.
Factory reset
Simply follow the instructions HERE. It will of course take a while to setup your phone again, but it’s so worth it.
Not enough?
You’ve got a little more HERE